The influence of the temperature on electron attachment to some halocontaining molecules

Thermal electron attachment rate coefficients for CH2ClCHClCH2Cl, CH2ClCH2Br, CH2ClCH2CH2Br and CF2ClCFCl2 have been measured using the Pulsed Townsend technique over the temperature range T = 298–358 K. The corresponding rate coefficients at 298 K are equal to 1.7(4) × 10−10, 7.9(15) × 10−10, 3.4(5) × 10−10 and 3.1(1) × 10−8 cm3 molec.−1 s−1, respectively. With rising temperature we have observed an increase of the rate coefficients k(T), which shows an Arrhenius-type behaviour. Activation energies Ea of 0.16(1) eV (CH2ClCHClCH2Cl), 0.12(1) eV (CH2ClCH2Br), 0.20(1) eV (CH2ClCH2CH2Br) and 0.08(1) eV (CF2ClCFCl2) were determined from the fit to the experimental data points with a function ln(k) = ln(A) − Ea/kBT.

The obtained rate coefficients for thermal electron capture by CH2ClCHClCH2Cl, CH2ClCH2Br, CH2ClCH2CH2Br and CF2ClCFCl2 show an Arrhenius-type rise with increasing the temperature. At constant temperature the log(k) on Ea gives, to good approximation, a linear dependence.Figure optionsDownload high-quality image (54 K)Download as PowerPoint slide