The combination band of ν2 + 2ν3 of CH4 at 1.33 µm (7512 cm-1) was observed at 0.3-cm-1 resolution by a simple experimental arrangement using a near-infrared high-radiant InGaAsP light emitting diode (LED) and a Ge detector. Forty-six line centers were measured with accuracies of 0.03 cm-1. The assignment of these manifolds was made by inspection of the P, Q, and R branches. The experimental result indicates that the ν2 + 2ν3 band can be used for fully optical remote monitoring of methane using InGaAsP optical sources in conjunction with an ultralow-loss optical fiber network.
© 1983 Optical Society of America
Kinpui Chan, Hiromasa Ito, and Humio Inaba, "Absorption measurement of ν2 + 2ν3 band of CH4 at 1.33 µm using an InGaAsP light emitting diode," Appl. Opt. 22, 3802-3804 (1983)