Atomic, Molecular, and Optical Physics (1986) / Chapter Skim
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8 Applications of Atomic, Molecular, and Optical Physics
8 Applications of Atomic, Molecular, and Optical Physics
Pages 151-174
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From page 151... ...
For lack of space, or because the information may not be publicly available, we have omitted a number of other major activities. Subjects that are entirely omitted, or are only discussed in passing, include environmental monitoring, optical data processing and optical computing, laser isotope separation, inertial confinement, photochemical processing, and laser weapons systems.
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From page 152... ...
Antennas at distant positions in the world observe radio waves emitted by distant radio galaxies and quasars. Hydrogen maser atomic clocks at each antenna synchronize recordings of the phase and amplitude of the signals to a fraction of a microsecond.
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From page 153... ...
These trapped ions can be used to create an optical frequency standard, that is, an atomic clock operating at an optical frequency rather than a microwave frequency. Neutral atoms have recently been slowed with laser light, even brought to rest in free space.
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From page 154... ...
f x7 1 Diode Infrared Laser (alcohol) , - 1 | Klystron ~ Diode X7 [ Very-Far-lnf fared Laser l T x7 | Klystron Diode 6)
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From page 155... ...
Fusion research also contributes to atomic physics, for the processes that occur under fusion conditions provide opportunities to observe at close range atomic phenomena that are rarely found on Earth, though they may be common elsewhere in the universe. Controlled thermonuclear devices burn isotopes of hydrogen to form an ash of helium and neutrons, with a prodigious energy release.
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From page 156... ...
. Data showing a single spike from the optical interferometer superimposed on the rapidly varying x-ray fringe are shown in (c)
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From page 157... ...
Understanding this process quantitatively is a vital problem for the fusion plasma modeling effort. Line radiation from impurities in the plasma is a valuable diagnostic probe of the reactant material.
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From page 158... ...
Experimental total cross sections for these processes have become available, but cross sections into particular final states need to be known, and these are so far available only theoretically. Inertial Confinement Many of the collision and spectroscopic parameters of concern to magnetic-containment fusion are also important in inertially contained plasmas.
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From page 159... ...
Atomic clocks and frequency standards are at the heart of our modern navigational systems. The accuracy of these devices is prodigious clocks with an accuracy approaching parts in 10'5 have been developed, and even higher accuracy appears to be possible.
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From page 160... ...
Atomic clocks in use include the hydrogen maser, the cesium atomic beam clock, and the optically pumped rubidium cell. The precision of these devices is ultimately limited by the second-order Doppler effect, the time dilation due to the motion of the atoms.
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From page 161... ...
One scheme for a millimeter/submillimeter detector exploits the high absorption cross sections of highly excited Rydberg atoms for very-longwavelength radiation. A pair of Rydberg states is chosen to be resonant with the incident radiation.
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From page 162... ...
The skills that AMO physicists acquire in atomic, molecular, and electronic processes; in optics and lasers; and in advanced experimental and theoretical techniques are vital to these programs. FIBER-OPTICS COMMUNICATIONS In fiber-optics communication light pulses representing digital information are launched from an electrically driven light source into a specially prepared glass fiber and are detected at the distant end and reconverted into electrical signals.
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From page 163... ...
It may be possible to do much of the signal processing that is now done electrically by processing the optical signals themselves rather than first converting them into electrical signals. This day may be rather far on, but there is no doubt that optical elements such as switches, polarizers, isolators, or wavelength division multiplex devices will be important parts of fiber-optic communication systems in the near future.
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From page 164... ...
The ability to achieve high temperature in short times permits laser processing of almost any material and opens the way to new machining, welding, annealing, heat treating, and chemical procedures. —Laser light is effectively inertialess and it can be focused with optical precision.
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From page 165... ...
At the end of the decade lasers will be commonplace in manufacturing plants ranging from small shops to heavy industrial plants and automated factories. The economic benefit to the United States from the use of lasers in manufacturing and materials processing is expected to be enormous: one survey estimates that lasers will lead to the creation of 600,000 new jobs in these areas (Newsweek, Vol.
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From page 166... ...
Using a small accelerator, ion-implantation methods allow impurities to be added free from the usual material constraints of diffusion and solid solubility. Ion bombardment can create electrically insulating layers or new surface alloys; ion-induced defects can induce material diffusion or ion-induced segregation.
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From page 167... ...
Nuclear Fusion Energy: Requirements include collision rates and cross sections for electron impact excitation, ionization, and dielectronic recombination; atomic-energy levels and wavelengths for identification of impurity elements in fusion plasmas, for plasma diagnostics and modeling, and for calculating plasma-cooling effects due to radiation from impurity atoms; photon mass attenuation coefficients and electron stopping powers are needed to design reactor blankets. Isotope Separation: Atomic-energy levels, transition probabilities,
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From page 168... ...
National Security: Atomic transition probability data are essential for modeling nuclear explosions in the atmosphere; photon attenuation data are needed to design shielding against ionizing radiation from nuclear weapons. Atomic-energy level, lifetime, and transition probability data are all needed for x-ray laser development.
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From page 169... ...
MEDICAL PHYSICS AMO physics contributes to the basic science of medicine and to the creation of new techniques for medical practice. We describe here two activities: laser surgery and NMR body imaging.
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From page 171... ...
Nuclear magnetic resonance provides a new way to form images of the body's interior using a noninvasive procedure that is believed to be without hazard. In contrast to x rays, magnetic resonance imaging can display the differences between soft tissues.
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From page 172... ...
Within the last 5 years two new variants of the MRI technique have emerged: proton imaging, which makes it possible to produce crosssectional pictures of the human body, and phosphorous imaging, which makes it possible to study physiological function in vivo over volumes of 50 cm3. For example, phosphorous imaging can distinguish between healthy and unhealthy tissue, providing information that can be crucial to cardiologists and peripheral vascular physicians.
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From page 173... ...
The development of MRI whole-body imaging required advances from many areas of science. Understanding of the magnetic resonance properties of nuclei in various media comes from studies in physical chemistry and biology; the superconducting magnets, which are essential parts of the imaging apparatus, are a product of low-temperature materials research.
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