Accession Number : ADB075328

Title :   Rotational-Vibrational Level Relaxation Effects on Laser-Induced Fluorescence Number Density Mesurements of Hydroxide in a Combustion Environment. I. Effects on Rotational Level Populations.

Descriptive Note : Interim rept. Oct 81-Sep 82,


Personal Author(s) : Campbell,D. H.

Report Date : MAY 1983

Pagination or Media Count : 53

Abstract : A full vibrational-rotational level rate equation model has been used to investigate the application of laser-induced fluorescence techniques to number density measurements of hydroxide in a combustion environment. The extent of deviation from the simple two-level model, due to rotational relaxation in the upper electronic state and quenching to lower-state vibrational bath levels, was investigated for a range of pressures, temperatures, and laser powers. Time resolved spectral measurements and high laser intensities were found to be crucial for accurate measurement of OH concentration when narrow bandwidth detection is used. For pressures much above one atmosphere, unattainable time resolution and laser powers are required if fluorescence from the laser pumped vibrational-rotational level only is measured. An alternative proposed shows promise of more accurate high-pressure OH concentrations. In this alternative, the total fluorescence from all upper laser-excited vibrational state rotational levels is measured after excitation with a low laser intensity. (Author)

Descriptors :   *Laser induced fluorescence, *Relaxation, *Molecular rotation, *Molecular vibration, Combustion, Hydroxides, Environments, Measurement, Density, Low intensity, Bandwidth, Narrowband, Detection, Atmospheres, Quenching, Pressure, Models, Spectra, Electronic states

Subject Categories : Lasers and Masers
      Nuclear Physics & Elementary Particle Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE