Cs(6P)激发态的辐射及与Ne碰撞的能量转移

Radiation and collisional transfer of excitation energy in Cs(6P) atoms mixed with Ne

应用激光吸收和荧光方法,测量了Cs(6P)态与Ne碰撞的精细结构转移和碰撞猝灭截面。Cs原子被激光激发到6P_(3/2)态,将与泵浦激光束反向平行的检测激光束调到6P_J→8S_(1/2)的跃迁,测量6P_J激发态的密度及空间分布,由此计算了6P_J→6S的有效辐射率.在T=337K和Ne密度0.5×10^(18)<N<4×10^(18)cm^(-3)范围内测量了6P_(1/2)→6S_(1/2)(895 nm)发射的敏化荧光强度I_(895),量N/I_(895)与N有抛物线型的关系,表明6P_J的猝灭是由于与Ne原子的碰撞产生的,而不是由与Cs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6P态与Ne碰撞精细结构转移截面σ_(21)=(1.90±0.82)×10^(-19) cm^2,猝灭截面σD_=(8.97±3.85)×10^(-19) cm^2.

Using the CW laser absorption and fluorescence method, the cross sections for the fine structure mixing and quenching of the Cs（6P） state, induced by collision with Ne atoms, were measured. Cesium atoms were optically excited to the 6P3/2 state. The excited atom density and spatial distribution were mapped by monitoring the absorption of a counterpropagating single mode laser beam, tuned to the 6PJ →8S1/2 transitions. The effective radiative rates were calculated for the 6PJ→6S transitions. The fluorescence intensity I895 of the sensitized 6P1/2→6S1/2 emission was measured as a function of Ne density in the range 0.5 ×10^18 〈 N 〈 4 × 10^18 cm^-3 at constant temperature T=337 K. It was found that the quantity N/I895 exhibited a parabolic dependence on N, confirming that the quenching of the 6PJ states is due to collision with Ne atoms, not with Cs ground state atoms. The coefficients of the second-order polynomial fitted through the measured data yielded the cross sections σ21 = （1.90 ±0.82） × 10^-19 cm^2 and σD = （8.97± 3.85） ×10^-19 cm^2 for the 6PJ fine-structure mixing and quenching, respectively, due to collision with Ne atoms.