Eigenanalysis of infrared mulitphoton decomposition kinetics

An eigenvalue/eigenvector analysis of the master equation for infrared multiphoton decomposition is used to derive a computational efficient means of analysing experimental data (such as fractional decomposition and, for multichannel reactions, branching ratios) to obtain laser absorption cross sections and information on gas/gas energy transfer. Reaction both during and after the pulse is incorporated, post-pulse collisional relaxation being found to be of both qualitative and quantitative importance in the interpretation of data. It is shown that fractional decomposition and branching ratios are essentially independent of the finer details of pulse shape, provided that the fluence remains fixed; it is am demonstrated that the analysis of the problem in terms of a single eigenvalue is inadequate.