State-to-state differential cross sections for the reaction Cl (2P32) + CH4 (ν3 = 1, J = 1) → HCl (v′ = 1, J′) + CH3

✍ Scribed by William R. Simpson; Andrew J. Orr-Ewing; Richard N. Zare

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 898 KB
• Volume: 212
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(93)87125-m

✦ Synopsis

A mixture of methane and chlorine molecules in a helium carrier is expanded into a vacuum chamber using a pulsed valve. Polarized laser photolysis of Clz at 355 nm is used to produce Cl(*P,,2) with a sharply peaked speed distribution and a known angular distribution. Methane molecules are excited in the asymmetric stretch mode by infrared absorption to the v~= 1, J= 1 state. Following a 100 ns time delay to allow for reaction, HCl( u' = I, J' ) product molecules are probed by (24 1) resonanceenhanced multiphoton ionization. The resulting photoions are detected with both mass and velocity resolution using a linear time-of-flight mass spectrometer. Application of the methods described by Shafer et al., allows determination of the differential cross section for the specific rovibrational state ionized at a center-of-mass collision energy of 0.159 eV. The time-of-flight data show a change in the product angular distribution with J' and thus demonstrate the importance of measuring quantum-stateresolved differential cross sections for elucidating the dynamics of this reaction system.