Rotational spectra provide measurement of the moments of inertia of a chemical species. Bond angles and bond lengths can be derived by making isotopic substitutions and measuring the resulting changes in the moments of inertia. A major drawback of rotational spectroscopies is the limited information contained in a measurement of the moment of inertia. Consequently, while quite precise, it is generally limited to smaller molecules. It is the chief technique used to identify molecules in outer space, such as the components of interstellar gas clouds.

Infrared and Raman spectroscopies provide complementary information concerning the type of functional groups present, as well as bond strengths in a molecule. Recent experiments using infrared pulse sequences offer the tantalizing possibility of bringing to infrared and Raman spectroscopies the same advantages that have been realized in pulsed NMR spectroscopies—greater sensitivity and higher information content. A major limitation of vibrational spectroscopies has been the congestion of overlapping features at lower frequencies. However this congestion makes an infrared spectrum a literal fingerprint of the structure of small molecules, so the identity of known molecules can be assessed from a library of their spectra. Some of the molecules in interstellar space have been identified by their infrared spectra. New resonant enhancement techniques can provide useful information about molecules on surfaces and at interfaces.

The interaction of species with shorter wavelengths of radiation causes electronic excitation (bound-bound electronic spectroscopy) or even ejection (bound-continuum photoionization). These events also show the fine structure of the motions of the nuclei. In addition, nuclear motions moderate the energies of the ejected electrons, and an analysis of the electron energy provides additional chemical information. Thus, x-ray photoelectron spectroscopy (XPS) is an excellent technique for determining an atom’s electron binding energies, at least for species on the surface of the material under study. Valuable information about surfaces can also be obtained from ultraviolet photoelectron spectroscopy (UPS), a technique that reveals ionization potentials and molecular orbital orderings for substances in general.

By comparing the chemical shifts and peak heights of an unknown with standards or known reference materials, some predictions of the unknown structure can be made. In some exceptional but important cases, such as the photodetachment of negative ions, the wavelength of light causing photoionization is in the visible or even the near infrared, allowing extremely precise structure determinations.

Front Matter (R1-R14)

Executive Summary (1-10)

1 Introduction (11-15)

2 The Structures and Cultures of the Disciplines: The Common Chemical Bond (16-21)

3 Synthesis and Manufacturing: Creating and Exploiting New Substances and New Transformations (22-40)

4 Chemical and Physical Transformations (41-54)

5 Isolating, Identifying, Imaging, and Measuring Substances and Structures (55-70)

6 Chemical Theory and Computer Modeling: From Computational Chemistry to Process Systems Engineering (71-94)

7 The Interface with Biology and Medicine (95-122)

8 Materials by Design (123-147)

9 Atmospheric and Environmental Chemistry (148-159)

10 Energy: Providing for the Future (160-170)

11 National and Personal Security (171-179)

12 How To Achieve These Goals (180-194)

Appendix A: Biographical Sketches of Steering Committee Members (195-201)

Appendix B: Statement of Task (202-202)

Appendix C: Contributors (203-208)

Index (209-224)