Design and performance of a low-temperature multiple-reflection absorption cell

Design characteristics and performance of a low-temperature multipass White cell are described. The optical pathlength can be varied from 40 m to 2000 m, and absorption measurements can be made under controlled temperature environment between 160 K and ambient temperature. The special feature of its construction, which combines White cell optics for laser applied spectroscopy and accurate temperature control, is that it allows the study of molecular fine structure of many species of both chemical and atmospheric interest. Spectroscopic measurements under conditions in which the temperature of the absorbing species is accurately known and pressure broadening is minimized provide information on molecular fine structure, populations of excited states, line intensities, and transition probabilities.