ABSTRACT
Methods of laser spectroscopy, which have been especially intensively developed since the early 70s of last century (Letokhov, 1987; Demtreder, 1985) allow to investigate the matter at the atomic and molecular levels with high sensitivity, selectivity, spectral and temporal resolution. Depending on the type of interaction of light with the test substance, these methods are divided into linear methods, methods based on single-quantum interaction, and non-linear method based on the non-linear single-quantum and multiquantum interaction.
