Theory of rotational polaron states of a diatomic impurity molecule in an atomic crystal

1988 ◽  
Vol 77 (2) ◽  
pp. 1167-1175 ◽  
Author(s):  
T. N. Antsygina ◽  
V. A. Slyusarev
Keyword(s):  
Impurity Molecule ◽  
Atomic Crystal

Low frequency Raman spectra of the liquid and plastic crystal phases of O2, N2, CO, and of Ar crystals with these molecules as guests

1982 ◽  
Vol 60 (9) ◽  
pp. 1358-1364 ◽  
Author(s):  
N. H. Rich ◽  
M. J. Clouter ◽  
H. Kiefte ◽  
S. F. Ahmad
Keyword(s):  
Single Crystals ◽  
Raman Spectra ◽  
Phonon Mode ◽  
Low Frequency ◽  
Impurity Molecule ◽  
Spectral Features ◽  
Background Impurity ◽  
Crystal Phases ◽  
Distinct Features ◽  
Frequency Feature

Low frequency Raman spectra of single crystals of orientationally disordered phases of oxygen, nitrogen, and carbon monoxide, and spectra of those substances as liquids show two linear segments in semi-log plots. Slopes of the higher frequency segments are nearly equal for all cases; slopes of the lower frequency segments are particular to the substance and are nearly the same in both liquid and crystal for O2 and CO. Spectra of single crystals of argon doped with O2, N2, or CO show two distinct features superimposed on a sloping background. Impurity molecule reorientation apparently accounts satisfactorily for all spectral features, but translation–rotation coupling may allow a contribution to the higher frequency feature arising from a local phonon mode in argon.

scholarly journals CH4 Adsorption Probability on GaN(0001) and (000−1) during Metalorganic Vapor Phase Epitaxy and Its Relationship to Carbon Contamination in the Films

Materials ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 972 ◽  
Author(s):  
Akira Kusaba ◽  
Guanchen Li ◽  
Pawel Kempisty ◽  
Michael von Spakovsky ◽  
Yoshihiro Kangawa
Keyword(s):  
Vapor Phase ◽  
Sequential Analysis ◽  
Chemical Potential ◽  
Control Method ◽  
Metalorganic Vapor Phase Epitaxy ◽  
Vapor Phase Epitaxy ◽  
Impurity Molecule ◽  
Surface Layers ◽  
Carbon Contamination ◽  
Potential Control

Suppression of carbon contamination in GaN films grown using metalorganic vapor phase epitaxy (MOVPE) is a crucial issue in its application to high power and high frequency electronic devices. To know how to reduce the C concentration in the films, a sequential analysis based on first principles calculations is performed. Thus, surface reconstruction and the adsorption of the CH4 produced by the decomposition of the Ga source, Ga(CH3)3, and its incorporation into the GaN sub-surface layers are investigated. In this sequential analysis, the dataset of the adsorption probability of CH4 on reconstructed surfaces is indispensable, as is the energy of the C impurity in the GaN sub-surface layers. The C adsorption probability is obtained based on steepest-entropy-ascent quantum thermodynamics (SEAQT). SEAQT is a thermodynamic ensemble-based, non-phenomenological framework that can predict the behavior of non-equilibrium processes, even those far from equilibrium. This framework is suitable especially when one studies the adsorption behavior of an impurity molecule because the conventional approach, the chemical potential control method, cannot be applied to a quantitative analysis for such a system. The proposed sequential model successfully explains the influence of the growth orientation, GaN(0001) and (000−1), on the incorporation of C into the film. This model can contribute to the suppression of the C contamination in GaN MOVPE.

Optical modification of a single impurity molecule in a solid

Nature ◽  
1992 ◽  
Vol 355 (6358) ◽  
pp. 335-337 ◽  
Author(s):  
Th. Basché ◽  
W. E. Moerner
Keyword(s):  
Impurity Molecule ◽  
Single Impurity

scholarly journals Signatures of an atomic crystal in the band structure of a C60 thin film

2020 ◽  
Vol 101 (16) ◽  
Author(s):  
Norman Haag ◽  
Daniel Lüftner ◽  
Florian Haag ◽  
Johannes Seidel ◽  
Leah L. Kelly ◽  
...  
Keyword(s):  
Thin Film ◽  
Band Structure ◽  
Atomic Crystal

scholarly journals Structure-mining: screening structure models by automated fitting to the atomic pair distribution function over large numbers of models

2020 ◽  
Vol 76 (3) ◽  
pp. 395-409 ◽  
Author(s):  
Long Yang ◽  
Pavol Juhás ◽  
Maxwell W. Terban ◽  
Matthew G. Tucker ◽  
Simon J. L. Billinge
Keyword(s):  
Distribution Function ◽  
Pair Distribution Function ◽  
Complex Oxide ◽  
Web Based ◽  
New Approach ◽  
Atomic Pair Distribution Function ◽  
Large Numbers ◽  
Traditional Structure ◽  
Atomic Pair ◽  
Atomic Crystal

A new approach is presented to obtain candidate structures from atomic pair distribution function (PDF) data in a highly automated way. It fetches, from web-based structural databases, all the structures meeting the experimenter's search criteria and performs structure refinements on them without human intervention. It supports both X-ray and neutron PDFs. Tests on various material systems show the effectiveness and robustness of the algorithm in finding the correct atomic crystal structure. It works on crystalline and nanocrystalline materials including complex oxide nanoparticles and nanowires, low-symmetry and locally distorted structures, and complicated doped and magnetic materials. This approach could greatly reduce the traditional structure searching work and enable the possibility of high-throughput real-time auto-analysis PDF experiments in the future.

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