Optical spectroscopy and current detection during warm-up and destruction of impurity–helium condensates

Abstract

New experimental results on detection of optical spectra and ion currents during destruction of impurity-helium condensates (IHCs) have been obtained. It is shown that emission during IHC sample destruction is accompanied by current pulses, pressure peaks and temperature changes. The molecular bands of excimer molecules XeO* are assigned to molecules stabilized in films of molecular nitrogen covering the heavier cores of impurity clusters which form impurity-helium condensates.

Quantum vortices and thermally induced luminescence of nitrogen nanoclusters immersed in liquid helium

“…Electrons and nitrogen anions were only detected during the process of destruction of the sample, where these species could be formed during the fast release of stored energy. [44,45] Additionally, none of the above mechanisms could explain the temperature dependence of the thermoluminescence observed in this work.…”

Defect‐induced electrostatic charging of nitrogen films

“…The experiments have revealed thermally stimulated exoelectron emission (TSEE) from preirradiated N 2 films that indicates the formation and accumulation of charged centers. Currents have also been recorded upon warm‐up of nitrogen‐containing impurity‐helium condensates IHCs . Creation of ionic species N 3 + and N 4 + in electron‐bombarded solid N 2 has been reported in Refs.…”

On charged impurity structures in liquid helium

“…This distinction along with last results on currents detected during destruction of IHCs [24,25] had allowed us to suggest existence of two different mechanisms responsible for "cold" and "hot" luminescence from IHCs.…”

“…The destruction of IHC sample starts with a sublimation of the helium shells surrounding impurity nanoclusters and preventing the recombination of nitrogen atoms stabilized on the nanocluster surfaces. Nitrogen atom recombination produces mainly metastable molecules N 2 (A 3 Σ) observable due to intense luminescence [24,25,27]. Then N 2 (A 3 Σ) molecules contacting with the beaker wall capture the electrons.…”

“…The currents detected during destruction of IHC samples containing stabilized radicals have revealed existence of charges in the condensates [24,25]. To find out a sign of charge carriers we have modified the geometry of electrodes (Fig.…”