Relation between photoacoustic amplitude and quenching of mercury 3P1→1S0 fluorescence by hydrogen in argon

Abstract

The quenching of mercury fluorescence excited by a modulated low-pressure mercury vapour lamp causes sound to be developed in the quench gas. Apparatus has been developed which allows the simultaneous measurement of fluorescence and acoustic signals as a function of quench gas composition. The amplitudes of the fluorescence and acoustic signals sum to a constant over the range of quench gas compositions from 0.01 to ca 1%, by volume, of hydrogen in argon. Normalized amplitudes therefore sum to unity. Similar results are also obtained by substituting helium for argon. The normalized amplitude of the acoustic signal is related to quench gas composition by a modified Stern–Volmer equation. Provisional quench reaction rate constants obtained from acoustic data at 295 K, using this equation, compare well with rate constants obtained from fluorescence data and also with literature values.