Studies of atoms and molecules using multiphoton absorption of ultraviolet laser radiation
The basic technique involves observation of fluorescent emission from gas samples irradiated by an ArF (193 nm) or KrF (248 nm) laser. First, collisional and photoabsorption properties of electronically excited H/sub 2/ are studied by means of selective excitation of the H/sub 2/ E,F /sup 1/..sigma../sub g//sup +/ double minimum state. The v = 2 level of the inner minimum of the E,F state is populated by two-photon absorption of ArF* laser radiation at 193 nm. The densities of the E,F rovibrational levels are measured by monitoring the near infrared E,F /sup 1/..sigma../sub g//sup +/ ..-->.. B /sup 1/..sigma../sub u//sup +/ fluorescent emission. Cross sections for ground state two-photon absorption to the E,F state and three-photon ionization are experimentally determined and are compared to calculated values. The E,F radiative life-time and collisional electronic and rotational relaxation rates are measured. The large electronic quenching cross sections (approx. 100 A/sup 3/) observed are attributed to collisional population of the C /sup 1/PI/sub u/ state, which is nearly degenerate with the E,F inner minimum. A theoretical model of inelastic scattering of H/sub 2/ E,F /sup 1/..sigma../sub g//sup +/ is developed and compared to experimental results. Two-photon excitation of Xe (5p/sup 5/6p) at 248 nm and of Xe/sup +/ and Kr (4p/sup 5/6p) at 193 nm forms the basis for another group of experiments.
- Research Organization:
- Stanford Univ., CA (USA)
- OSTI ID:
- 5909494
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400500 -- Photochemistry
640304* -- Atomic
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
COLLISIONS
CROSS SECTIONS
DENSITY
ELECTROMAGNETIC RADIATION
ELEMENTS
EMISSION SPECTROSCOPY
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
EXCITATION
EXCITED STATES
FLUIDS
FLUORESCENCE SPECTROSCOPY
GAS LASERS
GASES
HYDROGEN
INELASTIC SCATTERING
ION COLLISIONS
ION-MOLECULE COLLISIONS
IONIZATION
LASER RADIATION
LASERS
MATHEMATICAL MODELS
MOLECULE COLLISIONS
MONITORING
NONMETALS
PHOTOIONIZATION
PHYSICAL PROPERTIES
RADIATIONS
RELAXATION
SCATTERING
SPECTROSCOPY
TIME DEPENDENCE
VIBRATIONAL STATES