Mechanistic investigations of nonlinear optical and pressure effects in multiphoton ionization spectroscopy of atoms and molecules

Thesis/Dissertation · Thu Jan 01 00:00:00 EST 1987

OSTI ID:5617989

Li, L

Detailed experiments confirm the narrowing of ac Stark-broadened 2 + 2 multiphoton ionization (MPI) spectra of nitric oxide (NO) at room-temperature thermal equilibrium in a cell at pressures on the order of one Torr. Experiments with a supersonic beam of NO at comparable pressures exhibit no such narrowing. Both results can be predicted by a collective model depending on whether the molecular phases are random or coherent. The spectral line shapes obtained with different focusing geometries are successfully reproduced, which indicate a strong dependence of asymmetric broadening upon temporal and spatial inhomogeneities of a laser intensity. Multiphoton ionization spectra of chlorine reveal that photodissociation produces prominent lines and is also responsible for third harmonic generation (THG), which in turn excites some spin-forbidden transitions by one-photon absorption. Change and complications of state symmetry assignment by polarization technique in the presence of photodissociation and THG are discussed. Qualitative differences of third harmonic interference effects in atomic and molecular systems are also discussed. Details of the mysterious pressure effects in rare gas atoms are discussed in terms of MPI spectra of argon.

• Research Organization: State Univ. of New York, Stony Brook (USA)
• OSTI ID: 5617989
• Resource Relation: Other Information: Thesis (Ph. D.)
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
ARGON
MULTI-PHOTON PROCESSES
ATOMS
CHLORINE
MOLECULES
NITRIC OXIDE
STARK EFFECT
SPECTRA
CHALCOGENIDES
ELEMENTS
FLUIDS
GASES
HALOGENS
NITROGEN COMPOUNDS
NITROGEN OXIDES
NONMETALS
OXIDES
OXYGEN COMPOUNDS
RARE GASES
640302* - Atomic
Molecular & Chemical Physics- Atomic & Molecular Properties & Theory