The temperature dependence of the kinetic isotope effect in the reaction of F atoms with CH4 and CD4

The kinetic isotope effect k F + CH 4 / k F + CD 4 has been determined by reacting F atoms with mixtures of CH4 and CD4, using a discharge-flow-mass spectrometric technique. Experiments were carried out at four temperatures in the temperature range 183–298 K. The Arrhenius expression corresponding to the results is k F + CH 4 / k F + CD 4 = ( 0.99 ± 0.02 ) × exp [ ( 100 ± 5 ) / T ] . The present results are compared with previous published experimental and theoretical results.