Diffusion of hydrogen in rare gas solids: neutral H atoms and H+ protons

Abstract

In this letter we review and compare the available information about the stability and spectroscopy of the hydrogen atoms and protons in rare-gas solids. Mechanism of the H+ diffusion involving protonated rare-gas dimer Rg2H+ formation in the lattice is discussed. We suggest that the puzzling differences in their behavior and the stability are due to the fact that diffusion of hydrogen atoms is thermally activated, while that of the protons is activated by vibrational excitation of the Rg2H+ under ambient temperature blackbody radiation.

Neutralization of solvated protons and formation of noble-gas hydride molecules: Matrix-isolation indications of tunneling mechanisms?

“…The proposed electron tunneling mechanism should be considered as an alternative to the previously suggested mechanisms based on tunneling-supported or light-induced diffusion of protons in noble-gas lattices. 8,9 Secondly, we have found experimentally that the formation of HArF molecules occurs slowly but efficiently in photolyzed HF / Ar matrices already at 8 K. This remarkable phenomenon can be explained by the tunneling of a hydrogen atom, which is a probable mechanism based on the energetics calculated recently by Bihary et al 37 The tunneling mechanism is supported by the strong H/D isotope effect. The experimental data suggest that the HArF formation process is mainly independent of the decay of ͑ArHAr͒ + cations.…”

“…The tunneling and light-induced mechanisms for the global mobility of protons solvated in noble-gas solids were proposed by Beyer et al 8,9 These models could explain some previous experimental observations on the decay phenomenon of the cations, in particular, the isotope effect. Based on the present experimental data, the proposed models and additional possibilities can be reexamined.…”

“…For example, it was suggested that room-temperature background radiation could accelerate the diffusion of protons and deuterons in the matrix and explain the faster decay of protons. 8 More recently, it has been proposed that protons could diffuse via a tunneling mechanism. 9 In this model, proton diffusion is several orders of magnitude faster than that of deuterons, and the jump rate strongly increases from Xe to Kr and Ar, which is in qualitative agreement with the available experimental data on these species.…”

Nonpolar Dihydrogen Bonds—On a Gliding Scale from Weak Dihydrogen Interaction to Covalent HH in Symmetric Radical Cations [HnE‐H‐H‐EHn]+

“…There appear to have been only a few attempts to investigate chemical reactions initiated by radiation of noble gas/dihydrogen matrices. [24,25] …”

Ion–molecule reactions of CoAr6+ with nitrogen oxides N2O, NO, and NO2: measuring absolute pressure by shock-freezing of the collision complex

“…6 CoAr + is known to have octahedral symmetry [24,25], and its collision rate with neutral molecules should be well described with average dipole orientation (ADO) theory [26][27][28][29][30], a modification of Langevin collision theory [31] which includes the effect of a permanent dipole moment. Other candidates as pressure sensor ion are Ar 2 H + or 3 3 Ar H + [32][33][34][35]. For those species, however, the ion signal from our laser vaporization is less CoAr , + which would make routine application of the method difficult.…”