Infrared spectroscopy of radioactive hydrogen chloride H$^{36}\!$Cl

TL;DR

This study reports the first infrared spectroscopic measurements of radioactive hydrogen chloride H$^{36}$Cl, providing precise line data and molecular constants to aid in its detection and analysis.

Contribution

It presents the first optical absorption spectra of H$^{36}$Cl, including line positions and molecular constants, enhancing detection capabilities of this radioactive isotopologue.

Findings

Precise line center wavenumbers for H$^{36}$Cl were determined.

Rotational analysis yielded molecular constants for H$^{36}$Cl.

Linewidths and intensities were compared with stable isotopologues.

Abstract

We present the first report of optical absorption spectroscopy of H$^{36}\!$Cl, a radioactive isotopologue of hydrogen chloride. We used Fourier-transform infrared spectroscopy to determine the line center wavenumbers of the fundamental rovibrational band lines P(10)-R(10) and the first overtone band lines P(1)-R(7) with total uncertainty of less than 0.0018 cm$^{-1}$ (60 MHz) and 0.007 cm$^{-1}$ (0.2 GHz), respectively, at 68 % confidence level. We also performed a rotational analysis on the bands to determine the related molecular constants. We further compared the linewidths and relative intensities of the lines to those of the stable isotopologues H$^{35}\!$Cl and H$^{37}\!$Cl. The new spectroscopic information assists in developing optical instrumentation for the detection of H$^{36}\!$Cl.