Patrick McColgan

Patrick McColgan
Texas A&M University | TAMU · Department of Physics and Astronomy

Doctor of Philosophy

About

15
Publications
2,158
Reads
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75
Citations
Citations since 2016
11 Research Items
67 Citations
2016201720182019202020212022051015
2016201720182019202020212022051015
2016201720182019202020212022051015
2016201720182019202020212022051015

Publications

Publications (15)
Article
Full-text available
We studied the influence of rotation speed of a beaker containing superfluid helium (He II) on the intensity of luminescence of collections of nanoclusters immersed in He II. We observed an increase in the α-group emission of nitrogen atoms ( ² D→ ⁴ S transition) in nanoclusters which correlated with the increasing of rotational speed of the beaker...
Conference Paper
Full-text available
The helium plasma exhibits a rich network of processes involving energy transfer even at room temperature. Many neutral and ionic states of He atoms and He2 molecules are involved in the energy circulation in helium plasmas at cryogenic temperatures. Nevertheless, optical spectra of excited helium species are almost useless for the temperature dete...
Article
Full-text available
Impurity-helium condensates (IHCs) created by injection of nitrogen atoms and molecules as well as rare gas (RG) atoms (Ne, Ar, and Kr) into superfluid \(^4\)He have been studied via electron spin resonance (ESR) techniques. We investigated the influence of addition of rare gas atoms (Ne, Ar, and Kr) into the condensing \(\hbox {N}_2\)–He gas mixtu...
Article
Full-text available
We observed the appearance of a broad feature at 360 nm in spectra obtained during the destruction of ensembles of molecular nitrogen nanoclusters containing stabilized nitrogen, oxygen, hydrogen and deuterium atoms. We attribute this broad feature with a maximum at 360 nm to the N4 polynitrogen molecules which are the product of the neutralization...
Article
Full-text available
We have studied the luminescence of molecular nitrogen nanoclusters containing stabilized nitrogen, oxygen, hydrogen, and deuterium atoms. Optical spectra were observed during the destruction of these ensembles of nanoclusters accompanied by a rapid release of chemical energy stored in the samples. Several interesting features were observed includi...
Article
Full-text available
We studied optical and electron spin resonance spectra during destruction of porous structures formed by nitrogen–rare gas (RG) nanoclusters in bulk superfluid helium containing high concentrations of stabilized nitrogen atoms. Samples were created by injecting products of a radio frequency discharge of nitrogen–rare gas–helium gas mixtures into bu...
Article
We performed investigations of ensembles of molecular nitrogen nanoclusters, containing stabilized nitrogen atoms, immersed in liquid helium by electron spin resonance and optical spectroscopy. We observed thermoluminescence of nitrogen atoms and molecules via increasing temperature from 1.25 to 4.4 K. Two thermoluminescence maxima were observed, o...
Article
Full-text available
We studied the dynamics of thermoluminescence during destruction of porous structures formed by nanoclusters of nitrogen molecules containing high concentrations of stabilized nitrogen atoms. The porous structures were formed in bulk superfluid helium by injection of the products of discharges in nitrogen–helium gas mixtures through the liquid heli...
Article
Full-text available
Analysis of old and recent experiments on thermoluminescence of cryocrystals and nanoclusters of N2, Ne, Ar, and Kr containing stabilized nitrogen atoms, suggests that the so-called γ-line may correspond to the bound–bound transition 1D–3P of nitrogen anions N− formed in solids by the association of delocalized electrons and metastable nitrogen ato...
Article
We present the first observations of excimer XeO* molecules in molecular nitrogen films surrounding xenon cores of nanoclusters. Multishell nanoclusters form upon the fast cooling of a helium jet containing small admixtures of nitrogen and xenon by cold helium vapor (T = 1.5 K). Such nanoclusters injected into superfluid helium aggregate into porou...
Article
Full-text available
We describe a method for creating a high flux beam of cold atoms and molecules. By using this beam method, spectroscopic studies of the afterglow of oxygen-helium gas mixtures at cryogenic temperatures were performed. The cooling by helium vapor of a helium jet containing trace amounts of oxygen after passing through a radiofrequency discharge zone...
Article
Full-text available
We present the design and performance of an experimental setup for simultaneous electron spin resonance (ESR) and optical studies of nanoclusters with stabilized free radicals at cryogenic temperatures. A gas mixture of impurities and helium after passing through a RF discharge for dissociation of molecules is directed onto the surface of superflui...
Article
Full-text available
We present investigations of the afterglow of oxygen-helium gas mixtures at cryogenic temperatures. The cooling of a helium jet containing trace amounts of oxygen after passing through a radio frequency discharge zone led to the observation of strong emissions from atomic oxygen. The effect results from the increasing efficiency of energy transfer...

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