Experimental Study of the Fine-Structure Mixing of Cs 62P Induced By Collisions with Different Buffer Gases

Abstract

Fine-structure collisional transfer cross-sections for the 6²P_3/2 → 6²P_1/2 transition of caesium atoms in CH₄, C₂H₆, CH₄ + Xe, and C₂H₆ + Xe buffer gases were measured within the temperature range of 323–443 K using laser-induced fluorescence spectroscopy. The experimental results indicate that Cs(6P_J) atoms in C₂H₆ + Xe buffer gas exhibited the largest transfer cross-section in the 323–403 K temperature range. At 373 K, the fine-structure transfer cross-sections of Cs atoms in CH₄ and CH₄ + Xe gases were determined to be (11.40 ± 1.71) × 10^–15 cm² and (21.03 ± 3.15) × 10^–15 cm², respectively. Similarly, at 383 K, the fine-structure transfer cross-sections of Cs atoms in C₂H₆ and C₂H₆ + Xe gases were measured as (11.85 ± 1.78) × 10^–15 cm² and (40.33 ± 6.05) × 10^–15 cm², respectively. Charging with 24-Torr Xe gas increased the fine-structure transfer cross-sections in CH₄ and C₂H₆ gases by approximately 1.8-fold and 3.4-fold, respectively. Introducing Xe gas into CH₄ or C₂H₆ at 300 Torr within the 363–383 K temperature range markedly enhanced the D₁ and D₂ fluorescence intensities of the Cs atoms. The large collisional broadening coefficient of Xe contributed to improving the absorption efficiency of Cs atoms towards pump light. The experimental results presented in this study provide robust data support for enhancing the output performance of Cs-DPAL lasers under buffer gas pressures up to 500 Torr and enable effective validation of the relevant theoretical models.