An external-cavity diode laser (ECDL) has been used to investigate pressure-induced self-broadening as well as frequency shift of 2?3 band R9 manifold of methane. A phase sensitivity detection technology has been employed to determine the pressure induced frequency shift coefficient, however, which is obtained by line shape analyses of the recorded absorption spectrum. F1 and F2 unresolved double lines near 6105.626 cm^(-1) were measured as an object because they are often used to the high sensitivity detection of trace methane. The results show that the self-broadening and pressure induced frequency shift coefficients are 0.0232(+-)0.003 and 0.0055(+-)0.0007 MHz/Pa, respectively.
© 2005 Chinese Optics LettersPDF Article