3
Current Research Leadership Position

To determine the overall position of U.S. research in chemistry relative to research performed in other regions or countries, the panel analyzed journals (paper authorship, most highly cited articles, most accessed articles, and hot papers), international congress speakers, and prizes. Most of these measures have previously been used to assess quality of science; however, in addition, the panel used virtual congress evaluations to determine the leadership groups within each subarea. The limitations of each individual measure were recognized, and therefore, the panel analyzed the collective results of all of the indicators to draw conclusions regarding relative research competitiveness.

APPROACH

In this part of the overall benchmarking study, the panel tried to collect objective information as much as possible, but it also recognized its responsibility for making collective subjective judgments when needed. In addition, certain boundaries were needed to keep the exercise timely and relevant to the broad chemical enterprise.

In this exercise the panel considered individual countries and geographic regions, which include the United States (including Puerto Rico and any U.S. territories), Canada, Western Europe (including Greece), Japan, Asia, and “Other.”1

1

“Asia 13” includes Bangladesh, China (including Hong Kong), India, Indonesia, Malaysia, Pakistan, the Philippines, Singapore, South Korea, Sri Lanka, Taiwan, Thailand, and Vietnam. “Europe 17” includes Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, the Netherlands, Norway, Portugal, Spain, Sweden, Switzerland, and the United Kingdom. When data were gathered from different sources, the regional grouping of nations was sometimes inconsistent, hence producing the differences in the nomenclature used for the country groups.



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The Future of U.S. Chemistry Research: Benchmarks and Challenges 3 Current Research Leadership Position To determine the overall position of U.S. research in chemistry relative to research performed in other regions or countries, the panel analyzed journals (paper authorship, most highly cited articles, most accessed articles, and hot papers), international congress speakers, and prizes. Most of these measures have previously been used to assess quality of science; however, in addition, the panel used virtual congress evaluations to determine the leadership groups within each subarea. The limitations of each individual measure were recognized, and therefore, the panel analyzed the collective results of all of the indicators to draw conclusions regarding relative research competitiveness. APPROACH In this part of the overall benchmarking study, the panel tried to collect objective information as much as possible, but it also recognized its responsibility for making collective subjective judgments when needed. In addition, certain boundaries were needed to keep the exercise timely and relevant to the broad chemical enterprise. In this exercise the panel considered individual countries and geographic regions, which include the United States (including Puerto Rico and any U.S. territories), Canada, Western Europe (including Greece), Japan, Asia, and “Other.”1 1 “Asia 13” includes Bangladesh, China (including Hong Kong), India, Indonesia, Malaysia, Pakistan, the Philippines, Singapore, South Korea, Sri Lanka, Taiwan, Thailand, and Vietnam. “Europe 17” includes Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, the Netherlands, Norway, Portugal, Spain, Sweden, Switzerland, and the United Kingdom. When data were gathered from different sources, the regional grouping of nations was sometimes inconsistent, hence producing the differences in the nomenclature used for the country groups.

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The Future of U.S. Chemistry Research: Benchmarks and Challenges The assessment begins with an overall view of leadership in chemistry at large, looking broadly at science and engineering (S&E) and chemistry research outputs. This largely includes an analysis of journal articles and citations, virtual congress results, and to a lesser extent, information on international congresses and prizes. Finally, the areas of chemistry are described and assessed. JOURNAL ARTICLE CONTRIBUTIONS Publication of research results is essential for scientific and technological progress and leadership. Thus, looking at quantity and quality of journal articles being published in the world is one important and largely objective measure of scientific research leadership. For this analysis the panel selected a list of leading journals, with high impact factors. The impact factor is a measure of the frequency with which the “average article” in a journal has been cited. The impact factor of a journal is calculated by dividing the number of current year citations to the source items published in that journal during the previous two years. Given the broad range of journals in which chemists publish, and in an effort to assess current trends in the directions of fundamental chemistry research, the panel selected the journals as follows: Journals with broad coverage of S&E disciplines, in which chemists publish (e.g., Science, Nature) Journals with broad coverage of chemistry (e.g., Journal of the American Chemical Society, Angewandte Chemie) Leading journals for each subarea of chemistry: Area-specific journals where chemistry researchers are the primary contributors (e.g., Analytical Chemistry, Inorganic Chemistry) Area(s)-specific journals where researchers from various sciences and/or engineering disciplines publish, along with researchers from chemistry (e.g., Nature Materials, Physical Review Letters) The full list of all journals considered by the panel is given in Table C-1 in Appendix C. The panel focused its analysis of journal publications data on the following metrics: Publication rates over roughly the past 15 years (1988 to present) in all of science and in chemistry. Percent contributions by U.S. researchers in all areas of science versus those from other countries or regions.

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The Future of U.S. Chemistry Research: Benchmarks and Challenges Percent contributions by U.S. chemists versus those of chemists from other regions. Percent of papers in the list of 100 most cited papers for the periods 1990-1994, 1995-1999, and 2000-2006. To assess research leadership the panel concentrated on percent of hot papers, percent of highly cited papers, and the virtual congress results, which will be defined in more detail later in the report. For these criteria the following metric was used: Greater than 75 percent: the strong leader Greater than 50 percent: the leader Greater than 30 percent: among the leaders Less than 30 percent: lagging behind the leaders Here, we first look at the numbers of journal articles being published in S&E overall, in chemistry, and finally in chemistry area-specific journals. It is important to note that the overall percentage of papers contributed by a particular country indicates only the quantity of work performed, rather than quality. That is why numerous other metrics were applied to the assessment to gauge the quality of the chemistry research produced by each country. Decreasing U.S. Share of S&E Journal Articles Examination of the number of articles published annually in the scientific literature on a regional basis shows that the profile of scientific activity worldwide has changed dramatically over the past 15 years (see Figure 3-1). The long-standing scientific dominance of the United States persists, but other areas of the world are closing the gap. In 1988 the United States was the largest contributor to S&E publications, even when compared to other regions. While the absolute number of U.S. S&E papers grew by 19 percent between 1988 and 2003, the output of articles from Western European nations combined increased by 67 percent and surged past the U.S. total. Dramatic growth was seen for papers from Korea, which grew 1,683 percent from 771 to 13,746; China, 630 percent from 4,001 to 29,186; and Taiwan, 556 percent from 1,414 to 9,270. The percentage of papers from Asia and the subcontinent as a whole, which include China and India, has increased by a factor of 2.5, from 4 percent to 10 percent of all articles. The percentage of all S&E articles from U.S. authors dropped from 38 to 30 percent between 1988 and 2003.

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The Future of U.S. Chemistry Research: Benchmarks and Challenges FIGURE 3-1 Numbers of all S&E articles for select countries and regions. NOTE: Publication counts from set of journals classified and covered by Science Citation Index and Social Sciences Citation Index. Articles assigned to region/country/economy on the basis of institutional address(es) listed in article. Articles on fractional-count basis; i.e., for articles with collaborating institutions from multiple countries/economies, each country/economy receives fractional credit on the basis of proportion of its participating institutions. SOURCE: Regional and country portfolio of S&E articles, 1988, 1996, 2001, and 2003. National Science Foundation, 2006 Science and Engineering Indicators. The Fastest-Growing Economies Have Increased Their Share of U.S. Patent Applications While the number of U.S. patent applications from U.S. inventors more than doubled from 91,000 in 1990 to 189,000 in 2003, the percentage held steady at 55 percent.2 In contrast, U.S. patent applications from the fastest-growing economies (China, Hong Kong, India, Ireland, Israel, Singapore, South Korea, and Taiwan) increased more than eightfold from 3,800 in 1990 to 30,800 in 2003; their share of U.S. patent applications more than tripled, from 2.3 to 9.0 percent. 2 National Science Foundation, 2006, “U.S. Patent Applications, by Country/Economy of Origin of First-Named Inventor: 1990–2003 (Appendix Table 6-13),” Science and Engineering Indicators 2006.

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The Future of U.S. Chemistry Research: Benchmarks and Challenges TABLE 3-1 Top 10 Chemistry Paper Producing Countries (for 10-Year Period, Jan. 1996 to Nov. 2006) Rank Country Population (2006 est. in millions) Chemistry Papers Chemistry Papers/Million Inhabitants Total Papers 1 United States 300 217,791 726 2,831,004 2 Japan 128 117,085 915 771,573 3 Peoples Republic of China 1,300 102,047 78 400,917 4 Germany 82 95,815 1168 723,435 5 France 61 64,121 1051 522,015 6 Russia 143 60,765 425 280,480 7 England 61 57,199 938 643,557 8 India 1,100 47,556 43 203,989 9 Spain 40 40,179 1004 254,808 10 Italy 58 39,141 675 358,452 SOURCE: Thomson ISI Essential Science Indicators and U.S. Census Bureau, International Database. Decreasing U.S. Share of Chemistry Papers The number of a nation’s chemistry papers provides a quantitative measure of research activity in chemistry. According to Thomson ISI (which counts chemistry papers somewhat differently than the National Science Foundation (NSF)), U.S. chemists published more papers than those from any other country between 1996 and 2006 (see Table 3-1), accounting for about 18 percent of the total papers.3 The U.S. total is nearly twice that of second-ranked Japan. However, in looking at the numbers of chemistry papers published per million inhabitants, Germany ranks first and the United States is sixth. In addition, compared to other regions (see Figure 3-2), the United States ranks second to Western Europe and just slightly ahead of Asia. The trends in publication of chemistry papers show a leveling of U.S. activity in chemistry and growth in the rest of the world, except for the former Soviet republics (see Figure 3-3). Over the past decade the number of U.S. chemistry papers has remained relatively steady at about 15,000 annually. According to the NSF data shown, between 1988 and 2003 the percentage of articles contributed from both Western Europe and the United States dropped somewhat (from 22.9 to 19.1 percent for the United States), while the percentage from Asia (not Japan) more than tripled and now nearly matches the U.S. contribution. 3 According to Tomson ISI Essential Science Indicators accessed on November 15, 2006, the total sum of papers from 89 major contributing countries listed was 1,223,166.

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The Future of U.S. Chemistry Research: Benchmarks and Challenges FIGURE 3-2 Comparison of select country and regional production of chemistry papers, 1996 to June 2006. SOURCE: Thomson ISI Essential Science Indicators. Central/S FIGURE 3-3 Numbers of chemistry articles published in the world for select countries and regions. SOURCE: Regional and country portfolio of S&E articles, 1988, 1996, 2001, and 2003; National Science Foundation, 2006 Science and Engineering Indicators.

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The Future of U.S. Chemistry Research: Benchmarks and Challenges Figure 3-4 illustrates changes occurring in the contribution of U.S. and non-U.S. authors to American Chemical Society (ACS) journals. Since ACS journals are largely published in the United States by a U.S. organization, it is expected that U.S. authors would make the greatest contribution to these journals. However, the percentage of papers published by non-U.S. authors in American Chemical Society (ACS) journals has increased from 57 to 61 percent in the past six years shown. Contributions from Asia (largely due to China) doubled, from 6 to 12 percent. The increase in international papers in ACS journals reflects both the increasing popularity of the journals and the increasing ease of submitting papers electronically. It also indicates that the quality of non-U.S. papers is improving. Figure 3-5 shows the declining percent contributions of U.S. authorship in ACS journals for specific areas of chemistry. Chemistry Has a Small but Steady Share of U.S. S&E Article Output Only 8 percent of U.S. S&E articles are in chemistry, compared to the world average of 12 percent (see Figure 3-6). While the United States contributes 30 percent of the S&E articles, it contributes only 19.1 percent of the chemistry articles. The U.S. position may be indicative of a more diverse research portfolio or an emphasis on biomedical-related fields (see Figure 3-5). This trend may also be related to an increasing number of FIGURE 3-4 Percent contribution to all ACS journals from select regions. SOURCE: American Chemical Society, Publications Division.

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The Future of U.S. Chemistry Research: Benchmarks and Challenges FIGURE 3-5 Percent contributions of U.S. authors to ACS journals by (a) traditional and (b) emerging areas of chemistry. SOURCE: Analysis of data provided by ACS Publications Division. FIGURE 3-6 Percentage of a country’s articles that are in chemistry. SOURCE: Regional and country portfolio of S&E articles, 1988, 1996, 2001, and 2003; National Science Foundation, 2006 Science and Engineering Indicators.

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The Future of U.S. Chemistry Research: Benchmarks and Challenges publications in leading journals of other disciplines, due to the highly multidisciplinary nature of chemistry, especially in the United States. Figures 3-7, 3-8, and 3-9 show the different research portfolios of the United States, China, and India for 1996 and 2003. So far only data on the number of articles published in all of S&E and then in chemistry have been presented. The next section presents data that measure the impact and quality of publications. This information provides another measure of research leadership. JOURNAL ARTICLE CITATIONS This section looks at research quality through further analysis of article citations and papers deemed “hot” by Thomson ISI or that are most accessed through the ACS website. FIGURE 3-7 Research portfolio of the United States, 1996 and 2003. SOURCE: National Science Foundation, 2006 Science and Engineering Indicators.

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The Future of U.S. Chemistry Research: Benchmarks and Challenges FIGURE 3-8 Research portfolio of China, 1996 and 2003. Erosion of U.S. Lead in Journal Article Citations in Science and Engineering As mentioned earlier, Western Europe surpassed the United States in total S&E publications in 1997. While the United States still leads Western Europe in number of citations, the gap is narrowing (see Figure 3-10). The erosion of U.S. leadership in citations is due both to the increased number of publications and to the increased number of citations per paper from Europe. These data provide evidence that both the quantity and the quality of papers from Western Europe are increasing. U.S. Chemistry Leads in Total Citations and Citations per Paper The total number of citations of chemistry articles provides a measure of the strength of a nation’s contributions to chemistry, and the number of citations per paper gives information on the average impact of a nation’s chemistry papers. The United States ranks first both in total citations and in

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The Future of U.S. Chemistry Research: Benchmarks and Challenges FIGURE 3-9 Research portfolio of India, 1996 and 2003. SOURCE: National Science Foundation, 2006 Science and Engineering Indicators. citations per article in chemistry (see Table 3-2 and Figure 3-11). While U.S. authors published 18 percent of chemistry articles, their papers received 28 percent of the total world citations over the past 10 years.4 Thus, although the United States lags behind Western Europe in terms of number of chemistry articles (Figure 3-3), the average impact of a U.S.-authored article, measured by citations, is substantially greater than for those from Western Europe and other regions. Strong but Declining U.S. Contribution to Highly Cited Chemistry Articles To assess the national origin of the highest-quality papers, the top 100 most highly cited papers in chemistry over the past 10 years were exam- 4 According to Thomson ISI Essential Science Indicators (accessed November 15, 2006), the total sum of papers from the 89 major contributing countries listed was 10,654,721.

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The Future of U.S. Chemistry Research: Benchmarks and Challenges Nuclear and radiochemistry includes accelerator/reactor chemistry for isotope production, nuclear structure, neutrino chemistry, nuclear forensics, and archeometery. Understanding of nuclear and radiochemistry underlies the availability of adequate supplies as well as proper and safe use of radioactivity for energy production or radiomedicine. Twenty percent of electric power in the United States is supplied by nuclear reactors. It is possible that construction of new reactors in the United States will resume within the next decade. Similarly, the use of radionuclides in medicine, research, and industry is predicted to increase. In assessing the current status of the U.S. contribution to nuclear and radiochemistry, several subareas were considered: Basic nuclear science includes the synthesis of radionuclides, production of new elements, generation of radioactive and exotic nuclear beams, determination of nuclear properties, and applications of nuclear spectroscopy. The subarea of nuclear energy production and nuclear waste concerns include studies of fuel cycles for Gen IV and Post Gen IV reactors, environmental studies of radioactive wastes, studies of the effects of radiation on fuel materials and wastes, and transmutation of radioactive waste products to reduce their lifetimes. Environmental behavior of actinides includes studies of actinide interactions related to geochemistry; actinide interactions with microbes; and actinide redox reactions, speciation, and complexation. Nuclear forensics involves using nuclear signatures to define the origin of radioactive materials, stable isotope signatures to determine geolocation, and conventional forensic information (fingerprints and fibers) from radiological samples. Nuclear neutrino research includes neutrino experiments such as SNO, Super-Kamiokande, KamLAND, SAGE, and double-beta decay and theory of neutrino oscillations. Nuclear isotope production involves policy studies of facilities for research and development of isotope production, radiochemistry education, and the role of national laboratories in isotope R&D. Assessment The United States has been recognized as a leader in nuclear and radiochemistry since the end of World War II. However, this leadership is eroding. Most of the research in nuclear and radiochemistry in the United

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The Future of U.S. Chemistry Research: Benchmarks and Challenges States is carried out at national laboratories. The number of U.S. chemistry departments offering a specialization in nuclear chemistry has decreased continuously over the past 30 years. There has been a corresponding sharp decline in the numbers of Ph.D.s in nuclear and radiochemistry (23 U.S. Ph.D.s from 1970 to 1980 versus 12 Ph.D.s from 1990 to 2000). According to the 2005 ACS Directory of Graduate Research, only a dozen departments still have a program in nuclear chemistry and these typically have one or two active faculty members. The virtual congresses in nuclear chemistry were conducted a bit differently because of the smaller number of researchers in this community. Six individuals, all from the United States and five from national laboratories, were asked to develop a virtual congress in a different specialty area of nuclear chemistry. While the organizers were asked to pick about 20 congress participants, they provided an average of only 13 each. This is in contrast to many of the other areas of chemistry examined in this study, where most organizers had difficulty limiting themselves to only 20 names. Based on 52 percent representation from U.S. participants in the nuclear chemistry virtual congresses, the United States is considered the leader in this area. Other countries with significant representation are Germany, Japan, and the United Kingdom. Based on journal analysis, the United States is among or lagging behind the leaders. In 2005, 19 percent of articles in Radiochimica Acta, approximately 30 percent in the Journal of Radioanalytical Nuclear Chemistry, and 30 percent in Separation Science and Technology were from U.S. authors. Authors from Japan and Western Europe, particularly Germany, are major contributors to these journals. Examination of the most cited articles in the Journal of Radioanalytical Nuclear Chemistry shows that the United States and Japan were the two largest single-country contributors (each with 10-20 percent of the authors), but Western Europe made the strongest regional contribution. Authors from Western Europe also contributed the greatest number of most cited articles to Radiochimica Acta, followed by authors from the United States and Japan. Although the results from the virtual congress exercise show that the U.S. nuclear and radio chemists are still highly regarded, the declining number of U.S. nuclear and radiochemists, and the analysis of journal publications, all point to the United States being among the leaders or lagging behind the leaders in nuclear and radiochemistry. The United States Is Among the Leaders in Organic Chemistry Organic chemistry deals with all aspects of the chemistry of carbon compounds. Since carbon compounds, including fats, sugars, proteins, and nucleic acids, are the building blocks of all living organisms, there is

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The Future of U.S. Chemistry Research: Benchmarks and Challenges a strong linkage between organic chemistry and the chemistry of life processes. Organic chemists design and synthesize drugs to improve human health, agricultural chemicals to safeguard the food supply, commodity chemicals for use as personal care products, and polymers for use as structural materials or fibers for clothing. Organic chemists design processes to convert petroleum, coal, and biomass to fuels for transportation and a myriad of materials that enhance our daily lives. Because chemistry has become so multidisciplinary, there is strong overlap and synergy between organic chemistry and biochemistry, pharmaceutical sciences, macromolecular chemistry, materials chemistry, and inorganic chemistry. Organic chemists in turn rely on advances in analytical chemistry, physical chemistry, and computational chemistry. To assess the current status of the U.S. contribution to organic chemistry, five representative subareas of organic chemistry were examined: Synthetic organic chemistry involves developing efficient and selective new reactions and designing and implementing the synthesis of complex molecules, including those related to natural products. Medicinal chemistry and drug discovery is a more applied but crucial subarea of organic chemistry. Medicinal chemists design and synthesize new organic compounds to test as drug candidates. They seek to understand and exploit the interaction of organic compounds with living organisms to develop new therapies. Natural products chemistry involves the isolation of new materials from living organisms and determination of their structure and biological activity. Natural products chemistry often provides leads for new kinds of pharmaceutical activity. Physical organic chemistry focuses on discovering the mechanisms of reactions and understanding the chemical and physical properties of organic molecules in molecular terms. The development of new synthetic methods often gets its inspiration from mechanistic studies or from biological chemistry. Organocatalysis is the study of reactions that employ catalysts based solely on organic compounds. This is a recent area of intense interest and complements traditional catalysts based on transition metal complexes. Organometallic chemistry and homogeneous catalysis were discussed earlier as a subarea of inorganic chemistry. Increasingly chemists seek to find catalytic methods for synthesis.

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The Future of U.S. Chemistry Research: Benchmarks and Challenges Assessment The United States is among the leaders in most areas of organic chemistry. The virtual congresses in medicinal chemistry and drug discovery had a very high 69 percent representation from U.S. participants. Those in synthetic organic chemistry and physical organic chemistry had 60 percent of the chosen speakers from the United States. The virtual congresses in natural products chemistry, organocatalysis, and organometallic chemistry and homogeneous catalysis had 50 percent of the chosen speakers from the United States. Taken alone, the virtual congress data place the U.S. as the leader in organic chemistry. The virtual congress data also showed strength in synthetic organic chemistry Japan, the United Kingdom, Germany, Switzerland, and the Netherlands; strength in medicinal chemistry and drug discovery in Germany, Switzerland, the United Kingdom, and France; strength in natural products chemistry in Japan, Germany, and Israel; strength in physical organic chemistry in Germany, Switzerland, the United Kingdom, and Japan; great strength in organocatalysis in Germany and Japan; and strength in organometallic chemistry and homogeneous catalysis in Germany, Japan, Canada, the Netherlands, and Spain. Analysis of “hot papers” (May-June 2006) showed that organic chemistry had a strong representation with 52 of 200 papers and that U.S. authors contributed 32 percent of those papers. Synthetic organic chemistry with 46 hot papers (36 percent from U.S. authors and 45 percent from Western Europe) and organocatalysis with 24 papers (23 percent from U.S. authors and 58 percent from Western Europe) appear to be particularly hot areas. In addition, there were 31 hot papers (40 percent from U.S. authors and 40 percent from Western Europe) from the related area of organometallic chemistry and homogeneous catalysis. The hot papers analysis shows very strong competition from Western Europe. Taken alone, the data on hot papers places the United States among the leaders in organic chemistry. Analysis of Thomson ISI data on the most highly cited papers in organic chemistry journals showed a strong but declining contribution from U.S. authors, who accounted for 59 percent of the most highly cited papers from 1990 to 1994 and 47 percent from 2000 to 2006. In the same period, contributions from Western Europe rose from 27 to 29 percent, those from Japan increased from 6 to 13 percent, and those from China and India tripled from 2 to 6 percent. This publications analysis places the United States among the leaders in organic chemistry. It is important to mention that U.S. contributions were particularly strong to the outstanding organic publications of the Journal of Organic Chemistry (36 percent of all papers and 80 percent of the 40 most accessed papers from 2004 to 2005) and Organic Letters (41 percent of all papers

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The Future of U.S. Chemistry Research: Benchmarks and Challenges and 62 percent of the 40 most accessed papers from 2004-2005). In both of these journals, international organic chemists increased their contributions in the past five years from 61 to 64 percent and from 53 to 59 percent, respectively. The most active countries were Japan, China, Spain, Germany, France, the United Kingdom, and Canada. In more specialized journals, U.S. authors contributed 41 percent of the papers to the Journal of Medicinal Chemistry and 50 percent of the 40 most accessed papers from 2004 to 2005 (major international contributions from Italy, the United Kingdom, Germany, Spain, and Japan) and 22 percent of the papers to the Journal of Natural Products (major international contributions from Japan, China, Taiwan, Germany, Thailand, and Australia). Natural product discovery is often the first area to become strong in developing nations (often involving collaborations with Japan or European countries). The strong showing of U.S. and European Union chemists in medicinal chemistry reflects the strength of their countries’ pharmaceutical industries. The United States Is the Leader or Among the Leaders in Physical Chemistry Physical chemistry focuses on identification of the molecular-scale events that constitute chemical reactions in all phases: gases, liquids, and solids. The chemical reaction may be initiated thermally, by photon absorption, by interaction with electrons, by collisions with high-energy particles, or by interaction with a solid or liquid surface. Experimental characterization of reactive events involves determining the energy levels of reactants, transition states, and products; the motions of the reactants, transition states, and products as the reaction proceeds; and the interactions of the reactants, transition states, and products with the surrounding molecules. The reactants, transition states, or products may be neutral species, positive or negative ions and may be as small as a hydrogen atom or as large as a protein molecule or a nanoparticle. Physical chemists often uncover new processes that are then developed into techniques accessible to a wide range of scientists; an example is magnetic resonance imaging. Physical chemists also discover new species such as C60, which opened the new subareas of nanoscience. Thus, there is strong overlap and synergy between physics, chemistry, and all other chemistry areas, particularly analytical chemistry, macromolecular chemistry, and materials chemistry. Many techniques with origins in physical chemistry are also employed in the disciplines of physics, biology, chemical and environmental engineering, geology, and medicine. Physical chemistry experiments most often provide data to which theoretical predictions and computational results are compared.

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The Future of U.S. Chemistry Research: Benchmarks and Challenges To assess the current status of the U.S. contribution to physical chemistry, seven representative, but overlapping subareas of experimental physical chemistry were examined: Biophysical chemistry is physical chemistry applied specifically to systems of biological interest. This effort is also pursued extensively in physics, biochemistry, and biology departments for the purpose of improved drug design and medical procedures. Heterogeneous catalysis probes mechanisms of reactions that typically occur on metallic nanoclusters supported on insulators such as transition metal oxides. These studies relate directly to many commercial processes such as oil refining, hydrogen production, and food processing. High-resolution spectroscopy primarily employs optical techniques in the frequency domain with the goal of identifying molecular energy levels. The energy level information forms the basis of a wide range of analytical techniques employed in environmental and atmospheric monitoring. Reaction dynamics involves determination of the motions and energies of the reactants as they evolve through the transition state to the final products. A wide variety of optical, electronic, and scattering techniques are used to probe the dynamics of chemical reactions occurring in the gas, liquid, or solid phase as well as on surfaces. Such information is critical for designing more efficient reactions and processes in energy technology, drug production, and environmental cleanup. Single-molecule imaging and electronics is the study of single molecules by optical and/or electronic methods, including both understanding of single-molecule or nanotube electronic devices, and microscope and laser-based optical methods to characterize single species in complex environments, often in a biological or medical context. This effort is being pursued vigorously in physics, chemistry, and biology departments; in medical research; and in industrial development of new DNA sequencing methods. Surfaces and interfaces chemistry is the study of the structure and reactivity of liquid and solid surfaces. The surfaces may be extended or may be limited to the nanometer scale. The surface, often a transition metal, may be a catalyst for a chemical reaction. Such studies provide the fundamental principles of the commercially important area of heterogeneous catalysis, which is essential to fuel and metal production, food processing, and commodity chemical manufacturing. The surface may also be consumed as a reactant, such as in semiconductor etching. These studies provide the basic chemistry of the manufacturing of electronic components and devices.

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The Future of U.S. Chemistry Research: Benchmarks and Challenges Ultrafast spectroscopy primarily employs optical techniques to study molecular motion in the femtosecond to attosecond range. Assessment The United States is the leader in all areas of physical chemistry, according to the results obtained for virtual conferences organized by U.S. scientists. In addition, the United States is among the leaders in the vast majority of areas. according to the results obtained for conferences organized by non-U.S. scientists. The virtual congress in biophysical chemistry had very high representation, 77 percent, by U.S. participants, for congresses organized by U.S. scientists and 46 percent representation by U.S. participants when organized by non-U.S. scientists. The U.S. representation in congresses in reaction dynamics, high-resolution spectroscopy, ultrafast spectroscopy, and surfaces/interfaces was between 60 and 69 percent when organized by U.S. scientists and between 36 and 49 percent when organized by non-U.S. scientists. U.S. representation in the heterogeneous catalysis virtual congress was 58 percent when organized by U.S. scientists and 24 percent when organized by non-U.S. scientists. The virtual congress in single-molecule imaging and electronics had 65 percent of the chosen speakers from the United States when organized by U.S. scientists and 70 percent of the speakers when organized by a single non-U.S. scientist. The virtual congress data showed strength in biophysical chemistry for Germany, the United Kingdom, Japan, and Switzerland; strength in reaction dynamics and high-resolution spectroscopy for Taiwan, Germany, Switzerland, Italy, China, Canada, the Netherlands, and France; strength in ultrafast spectroscopy for Germany, Switzerland, Canada, the Netherlands, and France; strength in single-molecule imaging and electronics for Germany, Switzerland, the Netherlands, Japan, and Sweden; strength in surfaces/interfaces for Germany, Denmark, and Japan; and strength in heterogeneous catalysis for Germany, Japan, Denmark, the Netherlands, France, Switzerland, and Spain. The leadership of U.S. physical chemists is also demonstrated by their strong overall contributions to the Journal of Physical Chemistry A and B (about 35 percent of all papers and an average of 75 percent of the 20 most accessed papers from 2004 to 2005). In these two journals, international physical chemists have increased their contributions in the past five years from 57 to 65 percent. The most active countries were Japan, China, Spain, Germany, Italy, France, the United Kingdom, Sweden, Belgium, India, and Canada. Additionally, strong U.S. leadership in physical chemistry is apparent by the 40 percent rate for U.S. contributions of papers to the Journal of Chemical Physics. In journals that publish many but not exclusively physical chemistry topics, Physical Review Letters and Physical Review A, U.S. authors rep-

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The Future of U.S. Chemistry Research: Benchmarks and Challenges resent 43 and 32 percent, respectively, of the contributions. In the more specialized but not exclusively physical chemistry journals, U.S. authors contributed 35 percent of the papers in Langmuir and 23 percent of the papers in Surface Science. It should be noted that Surface Science is published in Europe. U.S. scientists were responsible for authoring 51.5 percent of highly cited physical and computational chemistry articles in 1990-1994, 47.3 percent in 1995-1999, and 49.8 percent from 2000 to 2006. Of the top hot papers, physical chemistry is the fourth most popular area of chemistry, accounting for 12.2 percent of the top hot papers from 2004 to 2006. The United States and Western Europe are responsible for most of the hot papers, contributing 50 percent and 43.8 percent, respectively. The Journal of Physical Chemistry A and B contained some of the most accessed ACS articles, with 65 percent (Part A) and 75 percent (Part B) of the articles coming from the United States. The United States Is Among Leaders in Theory/Computation Theoretical chemistry develops mathematical frameworks and formalisms to describe the chemical properties of molecular systems and their molecular interactions. Theoretical chemistry emphasizes the use of quantum and statistical mechanics to calculate the properties of molecular systems and to seek an understanding of chemical phenomena from first principles. The subarea of computational chemistry deals with the simulation of chemical processes or the calculation of chemical properties of molecules and the interaction among molecules. To assess the current status of the U.S. contribution to theoretical chemistry, three representative subareas were examined: Electronic structure and basic theory. Electronic structure is a branch of theoretical chemistry that develops computational methods derived from molecular quantum mechanics and applies these methods to help understand the chemical properties of molecules. Properties of molecules that electronic structure theory can determine include geometrical structures, rotational-vibrational (rovibrational) energy levels, electronic energy levels, photoelectron spectra, dipole moments, polarizabilities, and NMR spectra. Chemical properties of molecular systems not easily obtainable from existing experimental techniques can be predicted and evaluated from the application of electronic structure theory. Basic theory aims to develop new mathematical models to better describe the properties of chemical systems. Molecular dynamics simulations provide descriptions of molecular motion in chemical systems and of the time-dependent behavior of a molecular

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The Future of U.S. Chemistry Research: Benchmarks and Challenges system. These simulations also provide information about the structure, dynamics, and thermodynamics of large molecular systems, such as polymers, condensed phases, and biological systems. Computer-aided chemical discovery is a rapidly growing area of theoretical chemistry that develops mathematical models of chemical processes that enable extraction and evaluation of chemical information. The goal is to test new chemical concepts to facilitate the discovery of new drugs, fuel additives, and catalysts. Discovery information that includes genetic algorithms and neural network algorithms are examples of techniques being used to evaluate how chemical systems might behave or to predict the formulation for a desired chemical property that is needed. Assessment The virtual congresses in theoretical/computational chemistry overall had 50 percent of the chosen speakers from the United States. While this provides evidence of U.S. leadership, the United States is not the dominant contributor. In electronic structure and basic theory development, 47 percent of the virtual congress speakers were from the United States. A close examination of these virtual congresses showed that most of the U.S. speakers were over 50 years old, while invitees from Europe were younger. Western Europe is showing great strength, particularly in many aspects of electronic structure and basic theory development. In other areas such as Monte Carlo and molecular dynamics simulation methods, which were invented in the United States, a strong U.S. position has been maintained. The virtual congresses in the area of computer-aided discovery had 53 percent U.S. speakers and strong representation from Europe and Asia. Some organizers of the virtual congresses noted the declining U.S. leadership in electronic structure and basic theory development. One organizer attributed the decline to the fact that developing new electronic structure methods is a risky long-term investment and that the U.S. funding structure does not support this mode of operation. U.S. authors contributed 30 percent of the papers in the leading journals that include theoretical/computational chemistry papers (Physical Review Letters, Physical Review, Journal of Chemical Physics, and Journal of Physical Chemistry). Between 2001 and 2006, there was a significant decline from 50 to 28 percent in U.S. authorship of papers in the ACS journals list. Only eight of the 100 “hot” papers in chemistry came from theoretical/computational chemistry and only two of these came from U.S. authors. The largest numbers of hot papers in the theoretical/computational area came from Western Europe. These hot papers were split between electronic

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The Future of U.S. Chemistry Research: Benchmarks and Challenges structure simulation and computer-aided chemical discovery. No papers from basic theory development were among the 100 hot articles. SUMMARY Evidence for research leadership in chemistry comes from analysis of publications, citations, highly cited papers and chemists, virtual congresses, and prizes. The strength of chemistry research across the world is very great. Overall, the United States is the leader in chemistry but does not hold a dominant position. Excellent chemists in Europe and Asia provide stiff competition for U.S. chemistry. In 2003 the United States published 19 percent of the world’s chemistry papers. The number of papers that U.S. chemists publish has not grown and is steady at about 15,000 chemistry papers a year. The percentage of articles from non-U.S. authors in ACS journals has been increasing and is now 61 percent. U.S. chemists are the most prolific authors in high-profile journals such as Science, Nature, and JACS. U.S. chemists are also major contributors to the prestigious European journal Angewandte Chemie. U.S. chemistry leads in the total number of citations and in citations per paper. The citation rates for papers from Western Europe are 10 to 30 percent lower than for those from the United States. While U.S. chemists publish 19 percent of chemistry papers, their papers received 28 percent of the total world citations over the past 10 years. U.S. chemists contributed 50 percent of the 100 most cited chemistry papers. They now contribute 47 percent of the most cited papers in selected chemistry journals, down from 53 percent in 1990. Fifty percent of the world’s most cited chemists are from the United States. U.S. chemists have been the most successful in winning international awards, including Nobel prizes. Virtual congress analysis supports U.S. leadership in most areas of chemistry. U.S. chemistry is particularly strong in emerging cross-disciplinary areas such as nanochemistry, biological chemistry, and materials chemistry. Status of U.S. Leadership in Areas of Chemistry The United States is the leader in analytical chemistry, biological chemistry, chemistry education, inorganic chemistry, and in materials chemistry and nanoscience.

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The Future of U.S. Chemistry Research: Benchmarks and Challenges The United States is the leader or among the leaders in macromolecular chemistry, and in physical chemistry. The United States is among the leaders in atmospheric chemistry, organic chemistry, and theoretical/computational chemistry. The United States is among the leaders or is lagging behind the leaders in nuclear and radiochemistry.