Methane concentration and isotopic composition measurements with a mid-infrared quantum-cascade laser.
Opt Lett
; 24(23): 1762-4, 1999 Dec 01.
Article
em En
| MEDLINE
| ID: mdl-11543189
ABSTRACT
A quantum-cascade laser operating at a wavelength of 8.1 micrometers was used for high-sensitivity absorption spectroscopy of methane (CH4). The laser frequency was continuously scanned with current over more than 3 cm-1, and absorption spectra of the CH4 nu 4 P branch were recorded. The measured laser linewidth was 50 MHz. A CH4 concentration of 15.6 parts in 10(6) ( ppm) in 50 Torr of air was measured in a 43-cm path length with +/- 0.5-ppm accuracy when the signal was averaged over 400 scans. The minimum detectable absorption in such direct absorption measurements is estimated to be 1.1 x 10(-4). The content of 13CH4 and CH3D species in a CH4 sample was determined.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Isótopos de Carbono
/
Lasers
/
Metano
Idioma:
En
Revista:
Opt Lett
Ano de publicação:
1999
Tipo de documento:
Article
País de afiliação:
Estados Unidos