Cs(7DJ)+H2的反应与非反应碰撞转移截面的测定

利用激光泵浦-吸收技术,研究了在样品池中的Cs(7D_J)+H₂→CsH[X¹∑+(v″=0)]+H光化学反应过程。双光子激发Cs-H₂混合蒸气中Cs原子至7²D态,荧光中除有泵浦能级发生的直接荧光外,还包含由精细结构碰撞转移产生的敏化荧光,CsH分子是由7D原子与H₂间的三体碰撞反应产生的。利用780 nm激光测量了CsH X¹∑+(v″=0→v″=21)吸收带。△Ⅰ′和△Ⅰ″分别表示泵浦7D_3/2和7D_5/2时的吸收光强。解速率方程组,得到7D_3/2→7D_5/2和7D_5/2→7D_3/2精细结构转移截面分别为(1.3±0.3)×10^-14和(9.8±2.0)×10^-15cm²。从7D_J碰撞到7D以外态的截面分别为(4.0±1.0)×10^-15(对J=3/2)和(3.6+0.9)×10^-15cm²(对J=5/2)。Cs(7D_J)+H₂→CsH+H的反应截面分别是(1.4±0.5)×10^-16(J=3/2)和(1.1±0.4)×10^-16cm²(J=5/2),7D_3/2与H₂的反应活动...更多性大于7D_5/2。

Experimental evaluation of reactive and nonreactive cross sections in Cs(7D)+H2 collisions

The Cs(7DJ)+H2→CsH[X1∑+(v″=0)]+H photochemical reaction was studied in a cell experiment by laser pump-absorption technique. Using two-photon exitation of the Cs72D atomic level in a Cs-H2vapor mixture,the resulting fluorescence includes a direct component arising from the optically excited state and a sensitized component due to the collisionally populated fine-structure state. The CsH molecules are formed in three-body reactive collisions between exited Cs72D atoms and ground state H2 molecules. Nearinfrared absorption band CsH X1∑+(v″= 0 →v′= 21)near 780 nm was measured. The cross sections for the 7D3/2→7D5/2 and 7D5/2→7D3/2 fine-structure mixing are(1.3±0.3)×10－14 and(9.8±2.0)× 10－15cm2,respectively. The cross sections for collisional transfer from 7DJ to states other than 7D for J being 3/2 and 5/2 are(4.0±1.0)×10－15 and(3.6±0.9)×10－15cm2,respectively. The reaction cross sections [i.e.,Cs(7DJ)+H2→CsH+H]for J being 3/2 and 5/2 are(1.4±0.5)×10－16 and(1.1±1.4)×10－16cm2,respectively. The relative reactivity with H2 for two studied atoms is in an order of Cs(7D3/2)>Cs(7D5/2).