Experimental and Modelling Study of the Unimolecular Thermal Decomposition of CHF3

C. J. COBOS; A.E.CROCE; K. LUTHER; H.-J. TROE

Zeitschrift für Physikalische Chemie

OLDENBOURG VERLAG

Lugar: Munich; Año: 2011 vol. 225 p. 1019 - 1028

0942-9352

The unimolecular thermal decomposition reaction CHF3(+M)=CF2 +HF(+M) was studied in shock waves by monitoring the UV absorption of the forming CF2 radicals. The results of the present and previous experiments on the temperature and pressure dependence of the rate constants are analyzed in terms of unimolecular rate theory. Falloff curves for 1500¨C1900 K) are represented in terms of fitted limiting low pressure rate constants k0 = [Ar]1.1x1016exp(−53.0 kcal mol−1/RT ) cm3 mol−1 s−1, limiting high pressure rate constants koo= 1.25xÁ1015 exp(−75.8 kcal mol−1/RT ) s−1 from quantum-chemical calculations, and center broadening factors Fcent = 0.17(+/-0.01) including strong and weak collision contributions from unimolecular rate theory. With these results, approximate analytical expressions of the falloff curves well represent the measured and calculated rate constants over wide ranges of pressure and temperature.