Product kinetic and internal energy distributions via velocity-aligned Doppler spectroscopy: Technical report, May 1985-January 1987

Technical Report · Thu Jan 01 04:00:00 EST 1987

OSTI ID:5614557

Wittig, C

We developed a method of sub-Doppler resolution spectroscopy that is useful for determining kinetic energy distributions. With 'conventional' Doppler spectroscopy, it is almost impossible to obtain an accurate distribution from a line profile, even with the highest resolution, except when the distribution is quite simple (e.g., a delta function). This is due to the lineshape deriving from velocity components along the wave-vector of the probe radiation, k/sub probe/. However, by choosing only those species whose velocities are essentially parallel (or antiparallel) to k/sub probe/, this handicap is overcome. Here, one obtains the kinetic energy distribution along k/sub probe/, and the resolution is limited only by our ability to reject species with velocity components perpendicular to k/sub probe/. This rejection is done by spatial and temporal discrimination, using counterpropagating, overlapped, pulsed photolysis and probe sources. At long delays, molecules are detected which are aligned with k/sub probe/. We call the method velocity-aligned Doppler spectroscopy (VADS). We have perused several cases involving photodissociation of small molecules, in each case detecting H-atoms using sequential 2-photon ionization via Lyman-..cap alpha... We discern structure in the kinetic energy distribution which is attributed to internal excitation of the 'other' fragment, and resolution is limited by the dye laser bandwidth. In the case of HBr, we resolve the Br spin-orbit states, and with H/sub 2/S, we resolve the SH vibrational levels. 38 refs., 7 figs.

• Research Organization: University of Southern California, Los Angeles (USA). Dept. of Chemistry
• DOE Contract Number: FG03-85ER13363
• OSTI ID: 5614557
• Report Number(s): DOE/ER/13363-T1; ON: DE88003510
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500* -- Photochemistry
BROMIDES
BROMINE COMPOUNDS
CHALCOGENIDES
CHEMICAL REACTIONS
DECOMPOSITION
DISSOCIATION
DISTRIBUTION
DOCUMENT TYPES
DOPPLER EFFECT
DYE LASERS
ENERGY
ENERGY LEVELS
ENERGY RESOLUTION
EXCITED STATES
HALIDES
HALOGEN COMPOUNDS
HYDROGEN COMPOUNDS
HYDROGEN SULFIDES
IONIZATION
KINETIC ENERGY
LASERS
LIQUID LASERS
MULTI-PHOTON PROCESSES
PHOTOCHEMICAL REACTIONS
PHOTOIONIZATION
PHOTOLYSIS
PROGRESS REPORT
RESEARCH PROGRAMS
RESOLUTION
SPECTROSCOPY
SULFIDES
SULFUR COMPOUNDS
VIBRATIONAL STATES
WAVELENGTHS