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The report discusses completed and proposed research in atomic and molecular physics conducted at the Columbia Radiation Laboratory from July 1972 to June 1973. Central topics described include the atomic spectra and electronic structure of alkali metals and helium, molecular microwave spectroscopy, the resonance physics of photon echoes in some solid state systems (including Raman echoes, superradiance, and two photon absorption), and liquid helium superfluidity., Continuation of Contract DA-28-043-AMC-00099(E). See also AD-766 274. Sponsored in part by Grants AF-AFOSR-2685-74, NGR-33-008-191, and NSF-GH-38503.

Presented is the final report on a study of photon-echo generation and photon-echo behavior. Also mentioned is research on superradiance. A brief summary of the results, a listing of publications, scientific personnel and degrees awarded are provided., Continuation of Contract DA-31-124-ARO-D-224.

Contents: Atomic hyperfine structure; Atomic lifetimes; Atomic frequency standards; Microwave spectroscopy; Molecular beam maser spectroscopy; Optical radio-frequency double-resonance studies of molecular excited states; Interaction between a neutral beam and a conducting surface; Adiabatic demagnetization in the rotating frame; Photon-echo resonance in neodymium; Photon-echo resonance in ruby; Echo behavior in ruby; Raman echoes; Coherence effects in two-photon absorption; Frequency shifts in resonant systems; Superradiance and pulse propagation; Quantized rotation of superfluid helium; Velocity-dependent occupation of the helium II superfluid state., Continuation of Contract DA-28-043-AMC-00099(E). See also AD-728 826. Sponsored in part by Grants, AF-AFOSR-1454-68, AF-AFOSR-2180-72, Grant NGR-33-008-012, NSF-GP-1424 and NSF-GP-31336X.

The document contains reports in the fields of atomic physics, physics of molecules, resonance physics, and macroscopic quantum physics., Sponsored in part by Grants NGL-33-008-012, and NSF-GH-34407. See also report dated 30 Jun 72, AD-748 097.

Contents: Atomic physics; Physics of molecules; Resonance physics; Macroscopic quantum physics., See also Progress rept. no. 20, AD-711 546. Continuation of Contract DA-28-043-AMC-00099(E). Sponsored in part by Grants AF-AFOSR-1454-68, DA-ARO(D)-31-124-G972, NGR-33-008-012, NSF-GP-14243, and NSF-GP-16029.

New measurements of a number of basic atomic properties have been obtained. These include gF values for the autoionizing quartet states of rubidium, lifetimes of the autoionizing quartet states of helium, and the hyperfine constants and lifetimes of excited P states of lithium. Preliminary phases of an experiment to study electron excitation of atoms by a coincidence technique have been successfully tested. Work in molecular spectroscopy has been expanded. An optically pumped Rb85 maser is now within 1 dB of oscillation on the field-independent 3035.73... MHz transition. Photon-echo amplitudes in ruby have been measured as a function of excitation pulse separation, and the preliminary results are in agreement with theory. The Raman echo apparatus has been improved by the construction of a ceramic heat-pipe oven to contain the T1 vapor and the installation of a 300 MW laser., Prepared in cooperation with Columbia Univ., New York, Div. of Government Aided Research. Continuation of Contract DA-28-043-AMC-00099(E). See also AD-695 712.