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Current situation in studies of lifetimes of excited rovibronic levels for the H 2 , D 2 , T 2 , HD, HT, and DT molecules is analyzed. All measured values of the lifetimes, reported before November 2014, are compiled and listed in the tabular format together with annotated bibliography. Experimental data are now available for the H 2 , HD and D 2 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.

The subject of the present research is a quantitative study of opportunity to obtain a photoplasma in a low pressure mixture of alkali metal vapor and noble gas by concentrated solar (or gas lamp) irradiation. The ground, resonance and high-excitation levels, and atomic and molecular ions of an alkali metal were considered. The proposed self-consistent model along with plasma-chemical reactions and radiation transfer accounted for charge transport processes and ambipolar diffusion, unlike previous studies (LIBORS project and others). Spatial uniformity of resonance excitation rate in the all plasma volume was assumed. An iterative method to determine the main parameters of photoplasma was proposed and tested on the example of a mixture of Na vapor and Ar gas for pressures pNa = 0.02 and pAr = 1 Torr in a cylindrical cell of radius R = 0.005 m and length L = 0.01 m in the range of resonance radiation flux density Fλ0 = 4×(1–103) Wm−2 nm–1 inside the gas cell. The minimal value of resonance excitation rate, which is necessary to create a plasma in the considered gas cell, was evaluated as 1.1 × 1022 m−3 s−1. According to our rough estimation, to provide this rate, the minimal value of Fλ0 of an external source should be 40 Wm–2 nm–1. This can be implemented by the concentration coefficient of solar irradiation about 30. The model and obtained results can be used for the calculation of plasma parameters in different mixtures of an alkali metal vapor and a noble gas induced by a nonlaser irradiation source (concentrated solar or gas lamp irradiation) and designing of photovoltaic converters on their base.