Abstract:

The Cs(7D_J)+H₂→CsH[X¹∑⁺(v″=0)]+H photochemical reaction was studied in a cell experi- ment by laser pump-absorption technique.Using two-photon exitation of the Cs7²D atomic level in a Cs-H₂ vapor 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.Near- infrared absorption band CsH X¹∑⁺(v″=0→v′=21)near 780 nm was measured.The cross sections for the 7D_3/2→7D_5/2and 7D_5/2→7D_3/2fine-structure mixing are(1.3±0.3)×10^-14and(9.8±2.0)×10^-15cm², respectively.The cross sections for collisional transfer from 7D_J to states other than 7D for J being 3/2 and 5/2 are(4.0±1.0)×10^-15and(3.6±0.9)×10^-15cm²,respectively.The reaction cross sections [i.e.,Cs(TD_J)+H₂→CsH+H]for J being 3/2 and 5/2 are(1.4±0.5)×10^-16and...更多(1.1±0.4)×10^-16cm²,re- spectively.The relative reactivity with H₂ for two studied atoms is in an order of Cs(7D_3/2)>Cs(7D_5/2).  

Key words: spectroscopy, photochemical reaction, pump-absorption technique, cross section, Cs-H₂ mixture