## ABOUT INSTITUTE

Institute of Quantum Physics was founded in 2019 at Irkutsk National Research Technical University as a universal platform for advanced research in the field of quantum physics, combining the knowledge and experience of researchers working in leading Russian and foreign scientific institutions.

The priority of the Institute is to conduct original research in the field of quantum physics, focused largely on solving applied problems in the field of astrophysics, atmospheric physics, gas dynamics, molecular physics, etc. The development of the Institute should contribute to the formation and satisfaction of the demand for fundamental research in the field of quantum physics. including, due to the development of the school of theorists, the creation of modern laboratories for experimental research, the strengthening of cooperation between leading scientists and research centers.

## DEPARTMENT OF MOLECULAR SPECTROSCOPY

Vibrational phenomena have always fascinated scientists and engineers. A molecule constitutes a vibrational system of an important class that is mainly the subject of our present concern. High-resolution infrared absorption spectra provide information about the distribution of vibration-rotational energy levels and the transition probabilities of real molecules. Spectral lines command physical interest through their interpretation with the aid of physical models, i.e., the relation of frequencies and intensities of spectral lines to molecular motions of various types. As the precision of measurements made with various experimental techniques increases relentlessly, the interpretation of observed spectra becomes correspondingly challenging. This condition stimulates the search for, and development of, innovative methods to investigate vibrational systems for which a conventional description fails. Intuitively, the most natural model of intramolecular motions involves interacting anharmonic oscillations of atomic centers, but this simple physical model lacks a mathematically exact solution. The use of perturbation theory, however, solves the problem. This classical method is simple and clear, but its application is generally limited to the first few orders of theory that any textbook on quantum mechanics describes. The determination of corrections of higher orders becomes complicated through the sheer bulk of the calculations. The calculation of frequencies and intensities of spectral lines with an accuracy defined by experiment hence becomes difficult. A real spectrum of a sample containing even diatomic molecules of a particular chemical compound can comprise lines numbering a few thousands. Despite these difficulties, some success in developing an adequate method of calculation has been achieved, embracing perturbation theory.

## DEPARTMENT OF THEORETICAL MODELING

It is believed that the greenhouse effect is related to the parameters of absorption spectra of polyatomic molecules, usually trace gases, in planetary atmospheres. The main components of all known atmospheres of celestial bodies are symmetrical molecules that do not possess the dipole-allowed purely rotational (and in the case of diatomic molecules, vibrational–rotational) absorption spectrum. Upon increased pressure, a weak absorption appears, induced by intermolecular interaction, which can lead to a greenhouse effect. The contribution of the induced absorption in radiative forcing of a dense atmosphere may amount to a few or even tens of W/m2. In conditions typical for the atmospheres of terrestrial planets (including paleoatmospheres), the collision-induced absorption and associated greenhouse effect may lead to an increase in surface temperature above the freezing point of water. There is a correlation between the temperature of an atmosphere and the intermolecular bonding energy of gases that dominate in planetary atmospheres of the Solar System.

Within this research area we evaluate the general rules and features of the molecular composition of planetary atmospheres and the associated radiation characteristics of planetary systems. The relationship between the greenhouse properties of planetary atmospheres and their stability to the symmetry properties of their molecular components are discussed.