Ternary association of H+ion with H2at 11 K, experimental study

Abstract

The rate coefficient of the ternary association reaction H++2H2→H3++H2$ {\mathrm{H}}^{+}+2{\mathrm{H}}_2\to {\mathrm{H}}_3^{+}+{\mathrm{H}}_2$ has been measured at a temperature of 11 K using a 22-pole ion trap. The measurements were made over the density range of 0.5–10 × 10 13 cm −3 using normal hydrogen (with 1/4 p -H 2 and 3/4 o -H 2 ). We measured an apparent binary reaction rate coefficient and from the obtained linear dependence on the hydrogen density we calculated the ternary reaction rate coefficient k 3 = (3 ± 1) × 10 −29 cm 6 s −1 . From the measured data we can deduce that there exists very slow radiative association with the rate coefficient of the order of k r ≲ 3 × 10 −16 cm 3 s −1 at 11 K.