Infrared absorption spectrometer with a broad-band tunable He—Xe laser

Abstract

The performance of the infrared spectrometer with the tunable 3.5 μm He-¹³⁶Xe laser as a radiation source is characterized as follows: 1) the tuning coverage of 7 cm⁻¹ by a Zeeman laser with a superconducting solenoid is an order of magnitude broader than that reported in the past, 2) the source frequency modulation of specific amplitude, accompanied by synchronous detection, makes the output free from undulation due to mode hopping, 3) the highly directive laser beam is passed through an absorption cell of about 50 m effective path-length in which the Stark electric field is applicable to absorbing molecules. The high resolution and high sensitivity as well as the broad frequency coverage of the infrared spectrometer are demonstrated in the absorption spectra of some organic gas molecules.