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Atomic and Molecular Physics

The Center for Astrophysics | Harvard & Smithsonian Atomic & Molecular Physics division focuses on combined laboratory and theoretical studies of atomic and molecular processes; laboratory physics and astrophysics; atmospheric measurements; and atomic and molecular databases for astrophysics and atmospheric science.

Atomic & Molecular Physics (AMP) Research Activities

The full scientific potential of current and future generations of telescopes, across much of the electromagnetic spectrum from x-rays to radio waves, can be utilized fully only if the fundamental atomic and molecular physics data and their interpretation exist.

Research in the AMP division includes theoretical studies and laboratory and field measurements, which support astronomical observations at many wavelengths, address topics of astrophysical importance, and pursue related studies in fundamental physics and atmospheric science. Spin-offs from AMP research include current industrial, medical, communications, and environmental applications.

Studies of the processes of atomic, molecular, and optical physics and chemistry enable research in a number of astrophysics research areas.

Examples include:

  • Modeling of the chemistry of the early Universe clarifies the role molecules may have played in enabling the first generation of stars to form through gravitational collapse.

  • Calculations of molecule formation near supernovae and of the chemistry of interstellar clouds may explain a vast range of behavior in the Universe.

  • Analysis of spectroscopic observations being made with the instruments on board the Chandra X-ray Observatory enable AMP scientists to study the absorption of x-rays by atomic species. This research helps to explain the measured emissions of X-rays from comets and from the Jovian X-ray auroras over the polar caps.

  • AMP laboratory measurements coupled with radio astronomical investigations aim to understand the role of the chemical bond and organic chemistry in nature on a cosmic scale, and to determine the origin of the interstellar diffuse bands, the outstanding unsolved problem in astronomical spectroscopy.

  • AMP field measurements programs include satellite-based measurements of the Earth’s atmosphere, to study the photochemistry of the stratospheric ozone layer, and the global distributions of atmospheric pollution in the lower atmosphere.

  • Practical applications of theoretical work in AMP include modeling of the emitted light from sodium high-pressure lamps; this has led to measurements in the AMP laboratory used to understand the characteristics of the atmospheres of brown dwarf stars and gas giant planets.

New Physics

The CfA | Harvard & Smithsonian is also at the forefront of developing and applying novel technologies to high-sensitivity searches for new physics. This emphasis makes the AMP division unique in its experimental and theoretical strength, as it operates at the forefront of atomic and molecular physics.

The program attracts leading scientists, who may not have an astrophysics background, to an environment where their skills can be applied both to cutting-edge topics in terrestrial physics as well as to astrophysics. As examples:

  • Theoretical studies in fundamental physics include the interactions between matter and anti-matter. Recently, the field ionization and velocity spectra of strongly magnetized antihydrogen atoms were characterized and interpreted in collaboration with the ATRAP experimental group in the Harvard Physics Department.

  • The Institute for Theoretical Atomic, Molecular, and Optical Physics (at the Observatory) is a leading center for research on physics at ultracold temperatures (emphasizing Bose-Einstein Condensation).

  • Theoretical work on nanodevices include proposed nanocentrifuges and stabilizers to damp turbulence in nanosystems.

  • AMP research on atomic clocks and quantum optics includes precise tests of fundamental symmetries of physics (Lorentz invariance) which also address questions about the origin and fate of the universe:

    • Measurements on low temperature collisions between hydrogen atoms contribute to the understanding of basic atomic processes.

    • Stored light experiments in quantum optics show that information encoded in a light pulse can be transferred to an atomic system and then retrieved coherently, with potential applications to quantum computing, communications, and cryptography.

  • Other applications of AMP measurements include the development and application of new tools for biomedical imaging, like the improved MRI of the lung, and understanding laboratory plasmas, e.g., controlled nuclear fusion.

Data Archives

The CfA also demonstrates its leadership in the compilation and administration of standard databases. For example, SAO’s HITRAN (HIgh-resolution TRANmission molecular absorption database) is used for predicting and simulating transmission and emission of light in atmospheres. It is the world-standard reference database in molecular spectroscopy, with approximately 15,000 users worldwide. The journal article describing it is the most cited reference in the geosciences.

Visit the Data Archives Website