About explosive delayed desorption from methane-doped argon matrices

TL;DR

This study investigates delayed methane desorption from argon matrices under electron irradiation, revealing cluster formation, multiple desorption bursts, and correlations with hydrogen atom luminescence, advancing understanding of radiolytic processes in cryogenic matrices.

Contribution

It provides the first observation of delayed CH4 desorption at low concentrations and analyzes the mechanisms linking desorption bursts with hydrogen atom luminescence.

Findings

Delayed desorption observed at 0.1% CH4 concentration.

Multiple desorption bursts correlated with H atom luminescence.

Total particle yield linearly depends on CH4 concentration (1-10%).

Abstract

The features of delayed desorption from CH4-doped Ar matrices irradiated with an electron beam of subthreshold energy were studied. Radiolysis products were detected by emission spectroscopy. The total desorption yield was monitored by recording the pressure in the experimental chamber. Based on the analysis of the concentration dependence of delayed desorption bursts and their structure, an assumption was made about the formation of CH4 clusters in Ar matrices. At a high dopant concentration of 10%, up to three consecutive bursts were recorded. Delayed desorption from a sample doped with 0.1% CH4 was registered for the first time. A correlation has been found between the burst of particles and the flash of luminescence of H atoms. This seemingly contradictory observation of the correlation of the H atom content with the particle explosion due to their recombination was explained by analyzing the energy transfer and capture processes and the features of the energy structure of H2 molecule. A linear dependence of the total particle yield on the CH4 concentration in the range of 1-10% was found. The dynamics of intensity changes in the sequence of main flashes and their delay time were discussed.