Optical cell cooled by liquid nitrogen to study absorption spectra at a Fourier spectrometer
V.I. Serdyukov, L.N. Sinitsa, A.A. Lugovskoi, N.M. Emel'yanov
V.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Science, Tomsk, Russia
Keywords: Фурье-спектроскопия, спектр поглощения, метан, Fourier spectroscopy, absorption spectrum, methane
Abstract
A low-temperature 17.5 cm long vacuum cell with removable quartz, ZnSe, and KBr windows was designed for working with the Bruker IFS 125M high-resolution Fourier spectrometer. The cell provides a threshold absorption sensitivity of about 10-6 cm-1. The cell makes it possible to record the absorption spectra of gases in the region 1000-20000 cm-1 in the temperature range from 108 to 298 K with an error of ± 0.1 K. The 12CH4 absorption spectra in the range from 9000 to 9200 cm-1 at a pressure of 300 mbar and a spectral resolution of 0.03 cm-1 were recorded using an IFS 125M Fourier spectrometer at 298 and 108 K. The empirical values of the lower state energy levels were obtained from the ratios of line intensities measured at different temperatures.
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