The role of intensities in determining characteristics of spectroscopic networks
Abstract
Spectroscopic networks (SNs) are large, finite, weighted, undirected, rooted graphs, where the vertices are discrete energy levels, the edges are transitions, and the weights are transition intensities. While firstprinciples SNs are "deterministic" by definition, if a realistic transition intensity cutoff is employed during the construction of these SNs, a certain randomness ("stochasticity") is introduced. Experiments naturally build random graphs. It is shown on the example of the HD^{16}O isotopologue of the water molecule how intensities, in the present case onephoton absorption intensities, determine the structure as well as the degree distribution and edge density of SNs. The degree distribution of realistic computed SNs can be described as scale free, with the usual and well known consequences. Experimental SNs, based on measured and assigned transitions, also turn out to be scale free. The graphtheoretical view of highresolution molecular spectra offers several new ideas for improving the accuracy and robustness of information systems containing spectroscopic data. For example, it is shown that most all rotationalvibrational energy levels are involved in at least a few relatively strong transitions suggesting that an almost complete coverage of experimental quality energy levels can be deduced from measurements.
 Publication:

Journal of Molecular Structure
 Pub Date:
 February 2012
 DOI:
 10.1016/j.molstruc.2011.10.057
 Bibcode:
 2012JMoSt1009..123F