Investigating the spectroscopic characteristics of twelve isotopologues for the Ar–CO2 complex

Abstract In this paper, we perform a theoretical study of isotope effects for the Ar–CO2 complex. Based on the two-dimensional potential energy surfaces (PESs) for the ground and vibrational excited state, the rotational energy levels are obtained for twelve isotopologues of the Ar–CO2 complex via bound state calculations. Our predicted vibrational shifts and rotational constants display two interesting characteristics for these twelve isotopologues. Firstly, the vibrational shifts and rotational constants for these isotopologues are determined to be a linear relationship, which is in good agreement with the available experimental results. Furthermore, the linear relationship for the vibrational shifts and rotational constants can be classified into two types according to the 12C and 13C in the CO2 monomer. Then the vibrational shifts of the remaining nine isotopologues unobserved experimentally are deduced based on our theoretical predictions and available experimental data. Finally, the infrared spectra of ten isotopologues for the Ar–CO2 complex are accurately predicted.