Accession Number : ADA318479

Title :   New High-Pressure Diagnostic Technique.

Descriptive Note : Final technical rept. 1 Aug 93-31 Jul 96,

Corporate Author : STANFORD UNIV CA DEPT OF CHEMISTRY

Personal Author(s) : Zhare, Richard N.

PDF Url : ADA318479

Report Date : 21 OCT 1996

Pagination or Media Count : 8

Abstract : Our research goal was to develop nonintrusive, laser-based optical diagnostic tools for the investigation of trace amounts of molecular species in hostile environments such as plasmas, flashes, flames and other combustion forms. By extending our study on spectroscopic applications of degenerate four-wave mixing (DFWM), we proposed to exploit a new absorption technique, Cavity Ring-Down Spectroscopy (CRDS), which is, in many ways, complementary to other methods for the investigation of the transient species, radicals, and ions present in harsh luminous environments. A spatial profile of CH3 absolute concentration near the hot filament was determined by CRDS using a topological method - Abel inversion of the spatial profile of CH3 absorbance. No rotational lines are resolved from CH3 because of predissociation. A two-photon laser-induced fluorescence (LIF) scheme is proposed to measure atomic hydrogen. The spatial temperature profile near the filament at 20 Torr of pure H2 at different filament temperatures was measured in the same reactor we measured CH3. This measurement, combined with the CH3 spatial profile gives a better understanding of the two most important gas phase radical species in the hot-filament diamond CVD process.

Descriptors :   *HIGH PRESSURE, *DIAGNOSTIC EQUIPMENT, *OPTICAL INSTRUMENTS, TRANSIENTS, IONS, LUMINOSITY, SPATIAL DISTRIBUTION, MEASUREMENT, TEMPERATURE, ENVIRONMENTS, SPECTROSCOPY, METHYL RADICALS, LASER INDUCED FLUORESCENCE, MOLECULES, PLASMAS(PHYSICS), CHEMICAL VAPOR DEPOSITION, VAPOR PHASES, HYDROGEN, COMBUSTION, LASER APPLICATIONS, TOPOLOGY, ADVERSE CONDITIONS, PHOTONS, QUANTUM ELECTRONICS, FILAMENTS, ABSORPTION, FLAMES, ATOMIC STRUCTURE, HOT WIRE, CHEMICAL RADICALS, FLASHES.

Subject Categories : Lasers and Masers
      Inorganic Chemistry
      Physical Chemistry
      Atomic and Molecular Physics and Spectroscopy
      Optics

Distribution Statement : APPROVED FOR PUBLIC RELEASE