Analytical photon catalysis: Measurement of gas phase concentrations to 104/cm3

Abstract

A new analytic technique was developed to determine quantitatively the concentration of gas-phase species at concentrations well below the measurement capabilities of atomic absorption and mass spectroscopy. The method involves injecting an excess of an energetic metastable species, N2(A3Σ+u) in this experiment, into a gas stream containing the species to be measured, Bi in this case. Energy transfer from the metastable to the sample species results in excitation and subsequent rapid emission of light. The intensity of the light emitted at the wavelengths characteristic of the sample species is a function of, and hence a measure of, the concentration. Concentrations as low as 1.5×104/cm3 were measured. Greater sensitivity is possible with more efficient optical detection.

Measurement of Kinetic Rates for Carbon Monoxide Laser Systems.

“…15). In terms of energy transfer in the CO-C , sys tem , this k ine tic mechanis m can be wrtc ten as:…”

Determination of carbon in trichlorosilane by metastable transfer emission spectrometry

“…The apparatus developed for this technique was derived from that of Capelle and Sutton (8)(9)(10)(11) and is, in most respects, a routine microwave discharge apparatus. Minor modifications were made to accommodate the highly reactive TCS sample and to ensure reproducible discharge conditions.…”

Atmospheric pressure active nitrogen (APAN) - a new source for analytical emission spectroscopy

“…that a low pressure active nitrogen afterglow could be utilized as an excitation source for analytical spectroscopy (34)(35)(36)(37)(38). Detection of gas phase Bi and GeH^ down to 10^ atoms/cm^ and 10^ molecules/cm^, respectively, was demonstrated (34)(35)(36), The proposed mechanism of excitation involved energy transfer from metastable, active-nitrogen species generated in a microwave cavity. More recently, the same system has been evaluated as a selective detector for gas chromatography (37,38).…”