Rb(5P_J)与He的碰撞精细结构混合和猝灭(英文)

Mixture and Quenching of the Rb (5P_J) States Induced by Collisions with Helium Atoms

应用激光吸收和荧光方法,测量了Rb(5PJ)态与He原子碰撞的精细结构转移和碰撞猝灭截面.Rb原子被激光激发到5P3/2态,将与泵浦激光束反向平行的检测激光束调到5PJ→7S1/2的跃迁,测量5PJ激发态原子的密度及空间分布,由此计算了5PJ→5S的有效辐射率.在T=340K和He密度0.5×1017<N<4×1017cm-3范围内测量了5P1/2→5S1/2发射的敏化荧光强度I795,量N/I795与N有抛物线型的关系,表明了5PJ的猝灭是由于与He原子的碰撞产生的,而不是由与Rb基态原子碰撞产生的.由最小二乘法确定的二次多项式的系数得到5P态与He碰撞精细结构转移截面σ3/2→1/2=(1.84±0.61)×10-17cm2,猝灭截面σD=(1.07±0.30)×10-17cm2.

Applying the cw laser absorption and fluorescence method, the cross sections for the fine structure mixing and quenching of the Rb （5PJ） state, induced by collisions with He atoms have been measured, Rubidium atoms were optically excited to 5 P3/2 states. The excited atom density and spatial distribution were mapped by monitoring the absorption of a counterpropagating single mode laser beam, tuned to the 5PJ→7S1/2 transitions. Transmission factors were calculated for the 5PJ→5S transitions. The fluorescence intensity I795 of the sensitized 5P1/2→5S1/2 emission was measured as a function of He density in the range 0.5×10^17〈N〈4×10^17cm^-3 at constant temperature T = 340K. It was found that the quantity N/I795 exhibited a parabolic dependence on N , confirming that the quenching of the 5PJ states is due to collision with He atoms, not due to Rb ground state atoms. The coefficients of the second-order polynomial fitted through the measured date yielded the cross sections σ1/2→1/2 = （1.84±0. 61）×10^-17 cm^2 and σD = （1.07±0. 30）×10^-17 cm^2 for the 5PJ fine-structure mixing and quenching, respectively, due to collision with He atoms.