Philos Trans A Math Phys Eng Sci. 2012 Nov 13;370(1978):5066-73. doi: 10.1098/rsta.2012.0098.

Stabilization of H+-H2 collision complexes between 11 and 28 K.

Philosophical transactions. Series A, Mathematical, physical, and engineering sciences

Radek Plasil, Illia Zymak, Pavol Jusko, Dmytro Mulin, Dieter Gerlich, Juraj Glosík

PMID: 23028154 DOI: 10.1098/rsta.2012.0098

Abstract

Formation of H(3)(+) via association of H(+) with H(2) has been studied at low temperatures using a 22-pole radiofrequency trap. Operating at hydrogen number densities from 10(11) to 10(14) cm(-3), the contributions of radiative, k(r), and ternary, k(3), association have been extracted from the measured apparent binary rate coefficients, k*=k(r)+k(3)[H(2)]. Surprisingly, k(3) is constant between 11 and 22 K, (2.6±0.8)×10(-29) cm(6) s(-1), while radiative association decreases from k(r)(11 K)=(1.6±0.3)×10(-16) cm(3) s(-1) to k(r)(28 K)=(5±2)×10(-17) cm(3) s(-1). These results are in conflict with simple association models in which formation and stabilization of the complex are treated separately. Tentative explanations are based on the fact that, at low temperatures, only few partial waves contribute to the formation of the collision complex and that ternary association with H(2) may be quite inefficient because of the 'shared proton' structure of H(5)(+).

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• Journal Article