Spectroscopy of radioactive molecules 14CH4 and H36Cl
Spectroscopy of radioactive compounds has gained extensive interest in recent years. Especially radiocarbon dioxide 14CO2 has been under thorough study with the motivation to develop optical instrumentation for its detection, for example, in nuclear facilities [1,2]. Another important radioactive molecule found in nuclear facilities is radiocarbon methane 14CH4 . In a preliminary work , we reported the first absorption spectrum of 14CH4. More recently , we improved our results and reported high-resolution measurements and rotational analysis of the same fundamental asymmetric stretching vibrational band ν3(F2) of the molecule. We used a narrow linewidth, mid-infrared continuous-wave optical parametric oscillator combined with cantilever-enhanced photoacoustic spectroscopy and wavelength modulation spectroscopy to determine the line center wavenumbers of 43 rovibrational lines with 0.003 cm-1 uncertainty (95 % confidence level). In addition, a spectroscopic model was used in a non-linear least squares fit to confirm the experimental results and to determine the molecular constants. Our conference contribution presents this research on 14CH4 and on our yet unpublished Fourier-transform infrared spectroscopy measurements of the fundamental and first overtone rovibrational bands of H36Cl, a radioactive isotopologue of hydrogen chloride.
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