Ternary association of H⁺ ion with H₂ at 11 K, experimental study

Department of Surface and Plasma Physics, Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, Praha 180 00, Czech Republic

^a e-mail: Radek.Plasil@mff.cuni.cz

Received: 15 April 2011
Revised: 22 July 2011
Accepted: 16 September 2011
Published online: 28 October 2011

Abstract

The rate coefficient of the ternary association reaction 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 × 10¹³ cm⁻³ using normal hydrogen (with 1/4 p-H₂ and 3/4 o-H₂). 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 k₃ = (3 ± 1) × 10⁻²⁹ cm⁶ 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 cm³ s⁻¹ at 11 K.