High-resolution methane ν_3-band spectra using a stabilized tunable difference-frequency laser system*

Abstract

Techniques are described for drift compensation and scan calibration of a visible-to-infrared difference-frequency converter enabling high-resolution molecular spectra to be recorded with a precision and reproducibility of 5 × 10−4 cm−1. The capabilities of the spectrometer are illustrated by scans of the tetrahedral fine structure in the ν3 band of methane under low pressure, Doppler-limited and atmospheric pressure, collision-broadened conditions.