Son et Lumière or the Optoacoustic Effect in Multilevel Systems

Abstract

The theory of the periodically driven as well as of the pulse spectrophone is given for a gas with an arbitrary number of collisional excitation and de‐excitation reactions. The basic kinetic quantities are the rate constants which provide the most simple means of comparison with other experimental methods. No use is made of the methods of irreversible thermodynamics, but the approach is closely related to that theoretical concept. A matrix notation is used throughout since it provides the least complicated expressions and so eliminates possible sources of algebraic errors as well as programming errors in the case of numerical evaluations. Compared to the two‐level theory no additional assumptions are made. A link to the wealth of theoretical information available for the acoustic relaxation experiment is installed, especially for the case of mixtures of harmonic oscillators. The results are compared to those obtained by other means and examples are given.