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Atomic and Molecular Physics

Quantitative information about atomic and molecular processes required for interpreting astronomical observations is obtained from combinations of laboratory and theoretical studies. Laboratory research includes millimeter-wave through ultraviolet spectroscopy (millimeter-wave spectroscopy of molecules including anions that have recently been detected in space, long carbon chains and rings), and stored light experiments in quantum optics. Fundamental precision measurements to test time-reversal symmetry-violating phenomena and applications of new magnetic resonance imaging techniques using spin-polarized noble gases are pursued. Tests of general relativity and the underlying equivalence principle use laboratory experimental techniques as well as radio observations of solar-system objects, spacecraft, and quasars and measurements of the round-trip timing of laser pulses sent to the moon. The application of the laser frequency comb to astrophysical measurements has been developed and is being refined. The development of precise laser-based distance measurement techniques supports both the equivalence principle work and future space missions. Measurements of trace gases (primarily atmospheric pollutants and greenhouse gases) and other atmospheric constituents are made from satellite-based spectrometers operating in the ultraviolet, visible, and infrared.

Theoretical research with applications to astrophysics includes calculations of atomic and molecular structure, cross-sections for recombination and molecular collisional processes, photoionization, photodissociation, charge transfer, and the interactions between matter and anti-matter. These studies are used in the Atomic and Molecular Physics (AMP) division to explain the characteristics of X rays stemming from interactions of comets with the flux of ions and electrons streaming from the Sun (the solar wind), to examine the distributions of energetic atoms in atmospheres of the terrestrial planets, to develop new radiative transfer tools for the modeling of planetary atmospheres, and to measure and model photochemistry and pollution in the Earth’s atmosphere. AMP is a worldwide center for the development and archiving of fundamental spectroscopic parameters of molecular gases. These data are employed for calculations of transmittance and radiance for the Earth’s atmosphere and for astrophysics. The Institute for Theoretical Atomic, Molecular and Optical Physics, funded primarily by the National Science Foundation and situated in the AMP division, has now been in existence for twenty-two years. The main goals of the Institute are to educate both students and postdoctoral fellows in theoretical AMO Physics, to maintain a world-class visitor program, and to organize and support workshops in forefront areas of AMO Physics research.


BABB, James F., Physicist. A.B. (1982) Oberlin College; M.S. (1986), Ph.D. (1988) New York University. Research specialties: Applications of atomic and molecular physics to astrophysics and atmospheric physics; molecular structure; long-range forces.

CHANCE, Kelly V., Senior Physicist; Associate Director, Atomic and Molecular Physics Division, Harvard-Smithsonian Center for Astrophysics. B.S. (1970) University of Hawaii; A.M. (1972), Ph.D. (1977) Harvard University. Research specialties: Molecular spectroscopy, structure, and dynamics and their application to atmospheric studies; laboratory spectroscopy and satellite-based measurements of the Earth’s atmosphere, particularly of atmospheric pollutants and greenhouse gases; atmospheric composition and radiative transfer.

DALGARNO, Alexander, Senior Physicist; Phillips Professor of Astronomy, Harvard University. B.Sc. (1947), B.S. Advanced Studies (1948), Ph.D. (1951) University College, London; D.Sc. (1982) Queen’s University of Belfast; D.Sc. (2000) York University, Canada. Research specialties: Theoretical atomic and molecular physics; ultracold gases; chemical physics; interstellar medium; astrophysical plasmas; early universe; atmospheric physics.

KHARCHENKO, Vasili A., Physicist. M.Sc. (1974) Politechnic Institute (Leningrad); Ph.D. (1978), D.Sc. (1988) Ioffe Physico-Technical Institute (St. Petersburg). Research specialties: Atmospheric physics; atomic collision theory.

LIU, Xiong, Research Scientist, Smithsonian Astrophysical Observatory. B.S. (1995) Nankai University; M.A. (1998) Research Center for Eco-environmental Sciences, Chinese Academy of Sciences; M.S. (2002) University of Alabama in Huntsville; Ph.D. (2002) University of Alabama in Huntsville. Research specialties: Remote sensing of atmospheric trace gases, aerosols, and clouds; Atmospheric radiative transfer modeling and instrument calibration; Tropospheric chemistry studies integrating satellite measurements, chemical transport models, and in situ observations.

McCARTHY, Michael C., Senior Physicist. B.Sc. (1986) University of Alaska; Ph.D. (1992) Massachusetts Institute of Technology. Research specialties: Astrochemistry; laboratory astrophysics of reactive molecules; microwave and laser spectroscopy.

PHILLIPS, David Forrest, Physicist. B.S. (1988) California Institute of Technology; Ph.D. (1996) Harvard University. Research specialties: Development and applications of atomic clocks; precise tests of fundamental physical laws; quantum optics.

REASENBERG, Robert D., Physicist. B.S. (1963) Polytechnic University (Brooklyn); Ph.D. (1970) Brown University. Research specialties: Tests of general relativity, especially laboratory and space-based experiments to test the equivalence principle; solar-system dynamics and solar-system-based tests of general relativity; terrestrial and celestial applications of laser distance measurement.

ROTHMAN, Laurence S., Senior Physicist. B.S. (1961) Massachusetts Institute of Technology; A.M. (1964), Ph.D. (1971) Boston University. Research specialties: Molecular spectroscopy; HITRAN (high-resolution transmission) database compilation.

SADEGHPOUR, Hossein R., ITAMP Director. B.S. (1981), M.S. (1983), Ph.D. (1990) Louisiana State University. Research specialties: Atomic and molecular collisions and spectroscopy; formation and collision of cold antihydrogen and protonic atoms, quantum mechanical interference effects; rydberg collisions; absorption and scattering of light for astrophysical applications, recombination and reionization, and two-photon processes, coherent control and manipulation on the nanoscale, coherent light interaction with nanotubes, ultracold collision of dipolar systems.

WALSWORTH, Ronald L., Senior Physicist. B.S. (1984) Duke University; Ph.D. (1991) Harvard University. Research specialties: Development of atomic clocks and precision measurement tools; precise tests of fundamental physical laws; bioimaging and brain science; searches for extrasolar planets.

WANG, Huiqun, Physicist. B.S. (1997) University of Science and Technology, China; Ph.D. (2004) California Institute of Technology. Research specialties: Martian atmospheric chemistry and meteorology; planetary science; chemical transport models; General Circulation Models.


MARTIN, Randall V., Research Associate, Dalhousie University. B.A. (1996) Cornell University; M.Sc. (1998) Oxford University; M.S. (2001), Ph.D. (2002) Harvard University. Research specialties: atmospheric chemistry; satellite remote sensing; global modelling of atmospheric composition.

PHILLIPS, James D., Research Associate . B.S. (1975) University of Michigan; Ph.D (1983) Stanford University. Research specialties: Laboratory and space-based experiments on gravity; space-based astronomical optical instruments; measuring glacier motion with laser ranging.