Absorption coefficient measurements for trace amounts of methane are reported, in a 1-atm argon balance, at seventeen deuterium-fluoride (DF) laser line frequencies. An optoacoustic detector (spectrophone) operating within the DF laser optical cavity yielded a minimum detectable absorption of 0.007 km−1 (7 × 10−8 cm−1) for a 10:1 SNR. Results are compared with previous measurements and with calculated absorption coefficients obtained using the AFGL atmospheric absorption parameter compilations. A 2.5-fold increase in agreement results when the 1980 AFGL methane parameters are used instead of the 1978 parameters.
© 1981 Optical Society of America
D. H. Leslie and G. L. Trusty, "Measurements of DF laser absorption by methane using an intracavity spectrophone," Appl. Opt. 20, 1941-1947 (1981)