Document Type : Regular Article

Authors

• Najem Abdulkadhim Al-Rubaiey ¹
• Robin Walsh ²

¹ Department of Petroleum Technology, University of Technology-Iraq

² Department of Chemistry, University of Reading, Whiteknights, Reading, RG6 6AD, UK

Abstract

Time-resolved studies of silylene, SiH2, generated by laser flash photolysis of phenylsilane, PhSiH3 have been employed to obtain rate constants for its bimolecular reaction with deuterated hydrogen, D2. The monitoring laser was tuned to 17259.50 cm-1, corresponding to a known strong vibration-rotation transition, A (1B1)  X (1A1), in the SiH2 absorption band. The SiH2 concentration-time profiles were recorded for mixtures of phenylsilane and various partial pressures of D2 at temperatures in the range 300-553K. At three different temperatures, data were recorded in a series of runs for second order plots at 10 Torr total pressure. In addition to those experiments another set of runs was carried out at each temperature, in which the total pressure (SF6) was varied in the range 1 to 100 Torr in order to test the pressure dependence of the second order rate constants. In these runs second order kinetic behaviour was observed. The rate constants were found to be pressure independent. An Arrhenius equation was obtained with activation energy of E= -0.48 kCal/mol. The isotopic ratios obtained from experimental data for SiH2/SiD2 + D2/H2 were compared with those of Transition State Theory and found to be in reasonable agreement when the Transition State structure of Gordon et al was used.

Keywords

• flash photolysis kinetic
• isotopic
• silylene
• time-resolved