Lifetimes of vibro-rotational levels for excited electronic states of the diatomic hydrogen isotopologues

TL;DR

This paper compiles and analyzes lifetime data of vibro-rotational levels in diatomic hydrogen isotopologues, highlighting data gaps, discrepancies, and the need for more precise measurements and calculations.

Contribution

It provides a comprehensive compilation of lifetime data, identifies inconsistencies, and proposes recommended values for certain rovibronic levels.

Findings

Most levels have only one reported lifetime measurement.

Significant discrepancies exist between experimental and theoretical values.

Many data points lack independent verification.

Abstract

Current situation in studies of lifetimes of excited rovibronic levels for the H2, D2, T2, HD, HT, and DT molecules is analyzed. All measured values of the lifetimes (792 data for 618 different vibro-rotational levels of 33 electronic states), reported in 61 publications before November 2014, are compiled and listed in the tabular format together with annotated bibliography. Experimental data are now available for the H2, HD and D2 molecules only. The data collected in the present work show fragmentariness of experimental data. For vast majority of the levels the lifetime value was reported in one paper only, and has no independent experimental verification. Complete bibliography of publications concerning semi-empirical determination and non-empirical calculations of the lifetimes is presented. Numerical results obtained by these two approaches are listed in an explicit form only in the cases when experimental data are available. For more than half of the levels the differences between measured and calculated values are 3 times higher than experimental errors. This direct contradiction shows necessity of more precise experimental and non-empirical studies. For finite number of rovibronic levels our analysis made it possible to propose certain set of recommended data.