Mixing and quenching of the Cs 5DJ statesinduced by collisions with caesium ground-stateatoms

Abstract

Applying the cw laser absorption and fluorescence method the crosssections for the fine-structure mixing and quenching of thecaesium 5DJ states have been measured in pure caesiumvapour. Caesium atoms were optically excited to the 5D5/2 state via the quadrupole-allowed 6S1/2→5D5/2 transition. The ground-state caesium density N0, obtained from the absorption at the pumped quadrupoletransition, and the fluorescence intensity I689 of thesensitized 5D3/2→6S1/2 emission were measuredsimultaneously in the range 3×1014 cm-3⩽N0⩽1×1016 cm-3 at constant temperatureT = 585 K. It was found that the quantity N02/I689exhibited a parabolic dependence on N0,confirming that the quenching of the Cs 5DJ states isdue to collisions with Cs ground-state atoms, not molecules.The coefficients of the second-order polynomial fitted throughthe measured data yielded the cross sections σ5/2→3/2 = (57±19)×10-16 cm2 and σD = (35±10)×10-16 cm2 for theCs 5DJ fine-structure mixing and quenching,respectively, due to collisions with caesium ground-stateatoms. Using recently calculated Cs*+Cs potentials we performedan analysis which shows good agreement between the measuredvalues and the theoretical predictions.