Rb-N₂系统中碰撞转移截面的测定

Experimental Evaluation of Collisional Transfer cross Section in Rb-N₂ System

摘要: 激光激发Rb原子到5P_3/2激发态，测量了不同温度下Rb-N₂蒸气室中D₁线和D₂线的荧光强度比。实验结果表明，充入N₂压强在100~600 Torr时，Rb-N₂间有较强的电子–振动转动能量转移，Rb-Rb间的碰撞可以忽略。随着压强的增加，D₂线强度下降比D₁线更快。N₂压强在600 Torr时，D₁线和D₂线的荧光强度比随温度升高基本不变。建立并求解速率方程，得到323 K~353 K范围内Rb5PJ原子的精细结构转移截面平均值为σ₂₁ = (6.57 ± 1.64) × 10⁻¹⁶ cm²，σ₁₂ = (4.83 ± 1.21) × 10⁻¹⁶ cm²。Rb-N₂间的平均碰撞猝灭截面值为σ₁ = (1.80 ± 0.36) × 10⁻¹⁶ cm²。

Abstract: Rb atoms were excited to the 5P_3/2 state using a single-mode diode laser. The fluorescence intensity ratio of D₁ and D₂ line was measured at different temperatures in Rb-N₂ system. The experimental results show that when the N₂ pressure was filled at 100 - 600 Torr, strong electron-vibration rotational energy transfer between Rb-N₂ was produced, and collisions between Rb-Rb atoms could be ignored. The fluorescence intensity of D₂ line decreased faster than D₁ with the increase of pressure. The fluorescence intensity ratio of D₁ and D₂ lines was almost unchanged with the increase of temperature when the N₂ pressure at 600 Torr. By solving the rate equations, we obtained average value of fine structure transfer cross section of Rb5PJ atoms in 323 K - 353 K range. The values of the cross sections from Rb5P3/2 to 5P1/2 and from Rb5P1/2 to 5P3/2 were (6.57 ± 1.64) × 10⁻¹⁶ cm² and (4.83 ± 1.21) × 10⁻¹⁶ cm², respectively. The quenching cross section in Rb-N₂ collisions was (1.80 ± 0.36) × 10⁻¹⁶ cm².