Collisions of noble gases with supercooled sulfuric acid-water solutions

Dissipation of the excess energy of the adsorbate-thermalization via electron transfer

A new scenario for the thermalization process of adsorbates at solid surfaces is proposed. The scenario is based on the existence of an electric dipole layer in which the electron wavefunctions extend over the positive ions, creating a strong local electric field which drags the electrons into the solid interior and repels the positive ions. During adsorption the electrons tunnel into the solid interior, conveying the excess energy. The positive ions are retarded by the field, losing the excess kinetic energy, and are located smoothly into the adsorption sites. In such a scheme, the excess energy is not dissipated locally, avoiding melting or the creation of defects which is in accordance with experiments. The scenario is supported by ab initio calculation results, including density function theory of the slabs representing the AlN surface and the Schrodinger equation for the time evolution of hydrogen-like atoms at the solid surface.

Temperature Nonequilibration during Single-Bubble Sonoluminescence

Single-bubble sonoluminescence (SBSL) spectra from liquids having low vapor pressures, especially mineral acids, are exceptionally rich. During SBSL from aqueous sulfuric acid containing dissolved neon, rovibronic emission spectra reveal vibrationally hot sulfur monoxide (SO; Tv = 2100 K) that is also rotationally cold (Tr = 290 K). In addition to SO, excited neon atom emission gives an estimated temperature, for neon, of several thousand Kelvin. This nonequilibrated temperature is consistent with dynamically constrained SO formation at the liquid-vapor interface of the collapsing bubble. Formation occurs via collisions of fast neon atoms (generated within the collapsing bubble) with liquid-phase molecular species in the interfacial region, thus allowing for a mechanistic understanding of the processes leading to light emission.