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Baltenkov A.S.,Institute of Ion Plasma and Laser Technologies | Manson S.T.,Georgia State University | Msezane A.Z.,Clark Atlanta University
Journal of Physics B: Atomic, Molecular and Optical Physics | Year: 2015

Approximating the C60 shell as a collection of carbon atoms, the potential experienced by a confined atom has been calculated within the framework of the self-consistent spherical jellium model. It has been found that the potential well in this model has a cusp-shaped Lorentz-like profile. The parameters of the model Lorentz-bubble potential (depth and thickness) have been selected so that in the potential well there would be an electronic level corresponding to the experimental electron affinity of the C60 molecule. The spatial distribution of the positive charge of the C-atomic nuclei and the negative charge of the electron clouds forming the electrostatic potential of C60, as a whole, has been analyzed using the Poisson equation. It is demonstrated that the often used radial square-well potential to approximate the C60 corresponds to a non-physical charge density for the C60 molecule. This analysis demonstrates that the phenomenological potentials simulating the C60 shell potential should belong to a family of potentials with a non-flat bottom and non-parallel potential walls similar to the Lorentz-bubble potential. The photoionization cross-sections of a hydrogen atom localized at the center of the C60 shell have been calculated as well. It is found that confinement oscillations in the cross-sections are exhibited within the framework of the cusp-shaped potential model and these oscillations are essentially the same as those in the case of the potential wells with well-defined borders (parallel walls), thereby demonstrating that the inherent characteristic distances of the potential, e.g., radii of the potential walls, or the distances between potential walls, are not necessary to produce confinement resonances; this should be a general result for atoms or molecules confined in near-spherical fullerenes. © 2015 IOP Publishing Ltd.

Baltenkov A.S.,Institute of Ion Plasma and Laser Technologies | Msezane A.Z.,Clark Atlanta University
European Physical Journal D | Year: 2016

The effects of quantum confinement on the momentum distribution of electrons confined within a cylindrical potential well have been analyzed. The motivation is to understand specific features of the momentum distribution of electrons when the electron behavior is completely controlled by the parameters of a non-isotropic potential cavity. It is shown that studying the solutions of the wave equation for an electron confined in a cylindrical potential well offers the possibility to analyze the confinement behavior of an electron executing one- or two-dimensional motion in the three-dimensional space within the framework of the same mathematical model. Some low-lying electronic states with different symmetries have been considered and the corresponding wave functions have been calculated; the behavior of their nodes and their peak positions with respect to the parameters of the cylindrical well has been analyzed. Additionally, the momentum distributions of electrons in these states have been calculated. The limiting cases of the ratio of the cylinder length H and its radius R0 have been considered; when the cylinder length H significantly exceeds its radius R0 and when the cylinder radius is much greater than its length. The cylindrical quantum confinement effects on the momentum distribution of electrons in these potential wells have been analyzed. The possible application of the results obtained here for the description of the general features in the behavior of electrons in nanowires with metallic type of conductivity (or nanotubes) and ultrathin epitaxial films (or graphene sheets) are discussed. Possible experiments are suggested where the quantum confinement can be manifested. © 2016 EDP Sciences, SIF, Springer-Verlag.

Baltenkov A.S.,Institute of Ion Plasma and Laser Technologies | Msezane A.Z.,Clark Atlanta University
Journal of Physics: Conference Series | Year: 2015

An electronic structure of the negative ion C60 2- has been studied. It is found that in the first approximation of the variational method (when a trial wave function of the extra electrons is a product of one-electron functions) the total energy of the system is negative and that the second electron affinity (EA) of the C60 molecule within the utilized model potentials is about 1 eV. The photodetachment cross sections of the C60 2- ion have been calculated as well; they are found to exhibit two different threshold behaviors with their values being of the same order as the photodetachment cross sections of atomic negative ions with the same EA. © Published under licence by IOP Publishing Ltd.

Paiziev A.,Institute of Ion Plasma and Laser Technologies
NATO Science for Peace and Security Series B: Physics and Biophysics | Year: 2013

To improve diagnosis of brain injury (BI), it is critical to identify its symptoms early. We describe here a portable and cost effective device that may be able to detect BI in field. This report includes our recent publications devoted to devices based on near infra-red spectroscopy (NIRS) that can objectively detect, quantify, and record exposures that may cause BI as well capable of measuring changes in brain activity, physiology, or function that may be associated with BI. Another important task is to determine which devices are appropriate for use in the combat zone and civil environment, device size and ease of use. The results of the review revealed that empirical data characterizing BI in humans early after injury are lacking, making it difficult to critically evaluate and compare different devices and the measures they provide. Detailed consideration of many papers indicate that there is a critical need to determine the sensitivity and specificity of diagnostic devices in detecting BI, compare their ability to discriminate BI, and provide a better understanding of brain pathology and physiology immediately following injury. © 2013 Springer Science+Business Media Dordrecht.

Habib A.,Yamanashi University | Ninomiya S.,Yamanashi University | Chen L.C.,Yamanashi University | Usmanov D.T.,Yamanashi University | And 2 more authors.
Journal of the American Society for Mass Spectrometry | Year: 2014

(Figure Presented) In this work, desorption of nonvolatile analytes induced by friction was studied. The nonvolatile compounds deposited on the perfluoroalkoxy substrate were gently touched by an ultrasonic cutter oscillating with a frequency of 40 kHz. The desorbed molecules were ionized by a dielectric barrier discharge (DBD) ion source. Efficient desorption of samples such as drugs, pharmaceuticals, amino acids, and explosives was observed. The limits of detection for these compounds were about 1 ng. Many compounds were detected in their protonated forms without undergoing significant fragmentation. When the DBD was off, no ions for the neutral samples could be detected, meaning that only desorption along with little ionization took place by the present technique. © 2014 American Society for Mass Spectrometry.

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