New rovibrational subbands of Ar-D<sub>2</sub>O complex in the D<sub>2</sub>O bending mode region

The intermolecular interactions involving the water molecule play important roles in many fields of physics, chemistry, and biology. High-resolution spectroscopy Van der Waals complexes formed by a rare gas atom can provide wealth information about these interactions. precise experimental data be used to test accuracies efficiencies various theoretical methods constructing potential energy surfaces calculating bound states. In this work, high-resolution infrared absorption spectrum Ar-D<sub>2</sub>O complex <i>v</i><sub>2</sub> bending region D<sub>2</sub>O is measured using an external cavity quantum cascade laser. A segmented rapid-scan acquisition method employed. generated slit supersonic jet expansion passing Ar through vessel containing liquid D<sub>2</sub>O. Four new rovibrational subbands are assigned spectral range 1150–1190 cm<sup>–1</sup>, namely <inline-formula><tex-math id="M1">\begin{document}$\Sigma \left( {{0_{00}}, {v_2} = 1} \right) \leftarrow \Sigma {{1_{11}}} \right)$\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="1-20221728_M1.jpg"/><graphic xlink:href="1-20221728_M1.png"/></alternatives></inline-formula>, id="M2">\begin{document}$\Sigma \Pi xlink:href="1-20221728_M2.jpg"/><graphic xlink:href="1-20221728_M2.png"/></alternatives></inline-formula>, id="M3">\begin{document}$\Sigma {{1_{01}}, {{1_{10}}} xlink:href="1-20221728_M3.jpg"/><graphic xlink:href="1-20221728_M3.png"/></alternatives></inline-formula> id="M4">\begin{document}$\Sigma $\end{document}</tex-math><alternatives><graphic xlink:href="1-20221728_M4.jpg"/><graphic xlink:href="1-20221728_M4.png"/></alternatives></inline-formula><inline-formula><tex-math id="Z-20221230153751">\begin{document}$\leftarrow {{1_{01}}} xlink:href="1-20221728_Z-20221230153751.jpg"/><graphic xlink:href="1-20221728_Z-20221230153751.png"/></alternatives></inline-formula>. first two belong <i>otho</i>- species Ar-D<sub>2</sub>O, while latter <i>para</i>- species. observed transitions together with previously reported pure rotational spectra having common lower vibrational sub-states analyzed weighted least-squares fitting pseudo-diatomic effective Hamiltonian. An error 10 kHz for far-infrared 0.001 cm<sup>–1</sup> set global when Pickett’s program SPFIT, respectively. molecular constants including substate energy, centrifugal distortion constants, Coriolis coupling constant, determined accurately. previous results id="M5">\begin{document}$\Pi {{1_{11}}, 0} xlink:href="1-20221728_M5.jpg"/><graphic xlink:href="1-20221728_M5.png"/></alternatives></inline-formula> found likely incorrect. id="M6">\begin{document}$\Sigma xlink:href="1-20221728_M6.jpg"/><graphic xlink:href="1-20221728_M6.png"/></alternatives></inline-formula>and id="M7">\begin{document}$\Sigma xlink:href="1-20221728_M7.jpg"/><graphic xlink:href="1-20221728_M7.png"/></alternatives></inline-formula>substates experimentally time. band origin mode 1177.92144(13) which red shift 0.458 compared head monomer. its value based on four-dimensional surface includes normal coordinate mode. good agreement each other. But calculated levels generally higher than values, so, there still much room improving calculations.