Determination of absolute rate data for the reactions of atomic sodium, Na(32S1/2), with CH3F, CH3Cl, CH3Br, HCl, and HBr as a function of temperature by time-resolved atomic resonance spectroscopy

✍ Scribed by David Husain; Paul Marshall

• Publisher: John Wiley and Sons
• Year: 1986
• Tongue: English
• Weight: 770 KB
• Volume: 18
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.550180108

✦ Synopsis

We present a kinetic study of the reactions of ground-state sodium atoms with the molecules CH3F, CH3Cl, CH3Br, HC1, and HBr a t elevated temperatures (537-966 K). Na(32S,,2) was generated by the pulsed irradiation of various sodium halide vapors and monitored by time-resolved atomic resonance absorption of the unresolved D-lines at A = 589 nm [Na(3'PJ) + Na(3'S1,,)] in the "single-shot mode." The photoelectric signals were amplified without distortion, captured, and digitized in a transient recorder interfaced to a microcomputer for data analysis. Absolute second-order rate constants were measured at various temperatures in each case, yielding the following Arrhenius parameters (kRX = A exp(--E/RT), errors lu): RX A/10-" cm3 molecule s E/kJ mol-' CH3F CH3Br HCl CH3CI 82 t I 44 2 4

18 2 2 34 t 6 which constitute, to the best of our knowledge, the first direct measnrements of these quantities. The reaction between Na and HBr demonstrated anomalous behavior which is discussed in terms of potential surfaces that have been calculated previously for this type of collisional process. The data are compared with analogous results for Na + CF,, CF3Cl, and CF3Br and with single-temperature measurements on diffusion flames.