Optically pumped Hg2 studies

Abstract

The continuous emission bands of molecular mercury at 0.335 and 0.485 μm are excited in a pure mercury vapor by direct optical pumping of the weakly bound ground state molecules with a 5 nsec pulse of intense 0.266 μm radiation in order to study the radiative and collisional properties of the excited molecules at densities between 10¹⁴ and 10¹⁵ cm⁻³. Fluorescence time history of both bands are empirically analyzed in terms of dynamics governing the excited molecules. The analysis includes a density‐dependent nonexponential decay caused by bimolecular excimer quenching with a measured rate constant of k?2±1×10⁻¹⁰ cm³ sec⁻¹ molecule⁻¹. Because of interest in the mercury system as a potential laser medium, estimates of gain coefficients are derived from fluorescent power measurements. However, transmission measurements of the excited medium at 0.325 and 0.4416 μm show significant net loss due to excited state absorption with an estimated absorption cross section on the order of 10⁻¹⁷ cm² at 0.325 μm. Energy storage limitations implied by the bimolecular excimer quenching are also examined.