Chapter 1
Introduction
The book deals with processes that occurred in electronically-excited states of free
(isolated) small molecules as well as weakly-bound complexes and clusters. These
states can be populated due to the absorption of a photon (photochemistry) or
collisionally. In the latter case, a photon can radiate (photochemistry backward),
i.e., in photoprocesses.
Description of radiative population and decay of electronically excited states of
free molecules and weakly-bound complexes (clusters), as well as intra- and
intermolecular perturbations, is one of the fundamental problems of modern
chemical physics/physical chemistry and molecular spectroscopy. This information
is necessary for describing a wide range of processes occurring in the upper
atmosphere of the Earth and other planets as well as interstellar space, gas-phase
lasers, plasmas, flames, and so on. To describe gas-phase photoprocesses, one has
to use basic information on:
– Kinetics for chemical reactions, collisional and intramolecular processes
described in Chap. 2.
– The frameworks of the theory of elementary processes (Chap. 3).
The data given in these chapters are analyzed in a volume sufficient for
understanding the kinetics and mechanism of gas-phase photoprocesses in the
following chapters.
The principal goal of the book is a detailed description of:
Photolysis of free molecules, absorption and emission , intramolecular perturbation, dissociation, and electronic predissociation of di- and polyatomic molecules, the basic patterns of these processes are discussed in Chap. 4. Understanding
the mechanism of the electronically-excited state perturbations in free molecules
(intramolecular perturbation) is very useful for descriptions of nonadiabatic processes in more complex systems. Besides, a study of perturbations in free molecules
stimulates developments of the theory and accurate definition of molecule spectroscopic characteristics.
© Springer Nature Switzerland AG 2021
A. Pravilov, Gas-Phase Photoprocesses, Springer Series in Chemical Physics 123,
https://doi.org/10.1007/978-3-030-65570-9_1
1
Introduction
The book deals with processes that occurred in electronically-excited states of free
(isolated) small molecules as well as weakly-bound complexes and clusters. These
states can be populated due to the absorption of a photon (photochemistry) or
collisionally. In the latter case, a photon can radiate (photochemistry backward),
i.e., in photoprocesses.
Description of radiative population and decay of electronically excited states of
free molecules and weakly-bound complexes (clusters), as well as intra- and
intermolecular perturbations, is one of the fundamental problems of modern
chemical physics/physical chemistry and molecular spectroscopy. This information
is necessary for describing a wide range of processes occurring in the upper
atmosphere of the Earth and other planets as well as interstellar space, gas-phase
lasers, plasmas, flames, and so on. To describe gas-phase photoprocesses, one has
to use basic information on:
– Kinetics for chemical reactions, collisional and intramolecular processes
described in Chap. 2.
– The frameworks of the theory of elementary processes (Chap. 3).
The data given in these chapters are analyzed in a volume sufficient for
understanding the kinetics and mechanism of gas-phase photoprocesses in the
following chapters.
The principal goal of the book is a detailed description of:
Photolysis of free molecules, absorption and emission , intramolecular perturbation, dissociation, and electronic predissociation of di- and polyatomic molecules, the basic patterns of these processes are discussed in Chap. 4. Understanding
the mechanism of the electronically-excited state perturbations in free molecules
(intramolecular perturbation) is very useful for descriptions of nonadiabatic processes in more complex systems. Besides, a study of perturbations in free molecules
stimulates developments of the theory and accurate definition of molecule spectroscopic characteristics.
© Springer Nature Switzerland AG 2021
A. Pravilov, Gas-Phase Photoprocesses, Springer Series in Chemical Physics 123,
https://doi.org/10.1007/978-3-030-65570-9_1
1