Rb(5P_1/2)与N₂的精细结构碰撞实验研究

Experimental Study on Fine Structure Collision between Rb(5P_1/2)与N₂

摘要: 本文利用激光感应荧光光谱方法实验研究了激发态Rb(5P_1/2)原子在不同缓冲气体氮气压强下的碰撞能量转移过程。实验温度设定为295 K~473 K，氮气压强分别为100 Torr~500 Torr。利用钛宝石激光器输出794 nm连续激光激发Rb原子到5P_1/2激发态，测量了不同温度和缓冲气体压强条件下Rb原子的D₁线和D₂线荧光。通过建立稳态速率方程求解，得到了Rb原子D₁线和D₂线荧光强度比与碰撞对分子数密度的函数关系。通过实验数据的线性拟合给出了323 K~433 K范围内Rb(5P_J)原子的精细结构转移截面和猝灭截面。实验结果表明，Rb原子的精细结构转移截面随温度升高缓慢增加，分别约增大了3.12倍和2.39倍。Rb(5P_J)原子的猝灭截面随温度升高起伏振荡。在363 K~453 K温度范围内，氮气压强越大，Rb原子的D₂线转移荧光越强。Rb-N₂间的碰撞占据主导地位，加速了Rb(5P_J)能级间的精细结构能级混合。

Abstract: In this paper, the collisional energy transfer process of excited Rb(5P_1/2) atoms under varying nitrogen buffer gas is investigated using the laser-induction fluorescence spectroscopy method. The experimental temperature was set at 295 K to 473 K, and the nitrogen pressure was 100 Torr~500 Torr. The Rb atoms were excited to 5P_1/2 state by a continuous 794 nm laser emitted from a Ti: Sapphire laser. The D₁ line and D₂ line fluorescence of Rb atoms were measured at different temperatures and pressures of the buffer gas. By using the steady-state rate equation, we obtained the functional relationship between the fluorescence intensity ratio of Rb atom D₁ and D₂ lines and the impact on molecular density. The fine structure transfer cross sections and quenching cross sections of Rb(5P_J) atoms within the temperature range of 323 K~433 K were determined through linear regression analysis based on experimental data. The experimental results demonstrate a gradual increase in the fine structure transfer cross section of Rb atoms with rising temperature, exhibiting respective increments of approximately 3.12 and 2.39 times. The quenching cross section of the Rb(5P_J) atom exhibits oscillatory behavior as the tempera-ture increases. The D₂ line transfer fluorescence of Rb atom becomes stronger as the nitrogen pressure increases within the temperature range of 363 K~453 K. At this stage, the collision between Rb and N₂ assumes a dominant role in accelerating the mixing of fine-structure energy levels within Rb(5P_J) states.