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Papers by Victor G Thomas
Journal of Infrared, Millimeter, and Terahertz Waves, 2018
Petrology, 2014
In order to determine the mechanisms of formation and properties of natural hydrosilicate liquids... more In order to determine the mechanisms of formation and properties of natural hydrosilicate liquids (HSLs), which are formed during the transition from magmatic to hydrothermal mineral formation in gra nitic pegmatites and rare metal granites, the formation of HSLs was experimentally studied in the
Journal of Structural Chemistry, 2004
The contents of the structural channels of beryl, grown hydrothermally from an ammonium-containin... more The contents of the structural channels of beryl, grown hydrothermally from an ammonium-containing solution, were investigated by IR and EPR spectroscopy. Using IR spectroscopy we found that water molecules, ammonium ions, and a small number of HCl molecules enter the structural channels of beryl in the course of mineral growth. In these beryls, the ammonium ions play the role of alkali cations. The ammonium ions are as rigidly fixed in the lattice as are water molecules; they are eliminated by calcination at high temperatures close to the decomposition temperature. On exposure to radiation at 77 K, the paramagnetic 3 NH and H 0 radicals are stabilized in the structural channels of beryl. In addition to the known H 0 radical, other states of atomic hydrogen, interacting with medium protons, are observed as well. For one of the additional radicals, H b , we suggest the model of atomic hydrogen stabilized at the center of a silicon-oxygen ring with two water molecules in adjacent cavities.
Journal of Crystal Growth, 1999
ABSTRACT
Applied Magnetic Resonance, 2005
CrystEngComm
This study explores the fine structural details of the boundaries between the growth micro-sector... more This study explores the fine structural details of the boundaries between the growth micro-sectors in a ruby crystal grown hydrothermally on a nonsingularly oriented (011̄2̄) seed.
Crystal Growth & Design
A quantitative analysis of the evolution of a spherical surface artificially prepared from a pota... more A quantitative analysis of the evolution of a spherical surface artificially prepared from a potassium alum single-crystal during its regeneration is carried out in real growth experiments. The results are compared with the results of the numerical simulation based on the proposed regeneration process kinematical model. It is demonstrated that for many boundary conditions there is a close quantitative correspondence between the model and real experiments on the regeneration of single-crystal balls. It is shown that the most important parameter that has a quantitative effect on the growing regeneration surface evolution is the geometry of the roughness (protrusions and depressions), initially present on this surface. The rare quantitative discrepancies between the results of real growth and numerical experiments are due to the discrepancies between the geometry of the roughness set in the model and those actually present on the regenerating single-crystal ball. The proximity of the model to real regenerati...
Journal of Infrared, Millimeter, and Terahertz Waves
CrystEngComm
This study explores the fine structural details of the boundaries between the growth micro-sector... more This study explores the fine structural details of the boundaries between the growth micro-sectors in a leucosapphire (pure corundum, α-Al2O3) crystal grown hydrothermally on a nonsingularly oriented (01-1-2) seed. Numerous...
Crystal Growth & Design, 2016
Journal of Solid State Chemistry, Dec 1, 1998
Phase Transitions, 2014
When water is confined to nanocavities, its quantum mechanical behavior can be revealed by terahe... more When water is confined to nanocavities, its quantum mechanical behavior can be revealed by terahertz spectroscopy. We place H 2 O molecules in the nanopores of a beryl crystal lattice and observe a rich and highly anisotropic set of absorption lines in the terahertz spectral range. Two bands can be identified, which originate from translational and librational motions of the water molecule isolated within the cage; they correspond to the analogous broad bands in liquid water and ice. In the present case of well-defined and highly symmetric nanocavities, the observed fine structure can be explained by macroscopic tunneling of the H 2 O molecules within a six-fold potential caused by the interaction of the molecule with the cavity walls.
When water is confined to nanocavities, its quantum mechanical behavior can be revealed by terahe... more When water is confined to nanocavities, its quantum mechanical behavior can be revealed by terahertz spectroscopy. We place H 2 O molecules in the nanopores of a beryl crystal lattice and observe a rich and highly anisotropic set of absorption lines in the terahertz spectral range. Two bands can be identified, which originate from translational and librational motions of the water molecule isolated within the cage; they correspond to the analogous broad bands in liquid water and ice. In the present case of well-defined and highly symmetric nanocavities, the observed fine structure can be explained by macroscopic tunneling of the H 2 O molecules within a six-fold potential caused by the interaction of the molecule with the cavity walls.
The Journal of chemical physics, Jan 14, 2014
Low-energy excitations of a single water molecule are studied when confined within a nano-size ca... more Low-energy excitations of a single water molecule are studied when confined within a nano-size cavity formed by the ionic crystal lattice. Optical spectra are measured of manganese doped beryl single crystal Mn:Be3Al2Si6O18, that contains water molecules individually isolated in 0.51 nm diameter voids within the crystal lattice. Two types of orientation are distinguished: water-I molecules have their dipole moments aligned perpendicular to the c axis and dipole moments of water-II molecules are parallel to the c-axis. The optical conductivity σ(ν) and permittivity ɛ'(ν) spectra are recorded in terahertz and infrared ranges, at frequencies from several wavenumbers up to ν = 7000 cm(-1), at temperatures 5-300 K and for two polarizations, when the electric vector E of the radiation is parallel and perpendicular to the c-axis. Comparative experiments on as-grown and on dehydrated samples allow to identify the spectra of σ(ν) and ɛ'(ν) caused exclusively by water molecules. In th...
Journal of Physics: Conference Series, 2014
ABSTRACT
The Journal of Physical Chemistry Letters, 2013
When water is confined to nanocavities, its quantum-mechanical behavior can be revealed by terahe... more When water is confined to nanocavities, its quantum-mechanical behavior can be revealed by terahertz spectroscopy. We place H 2 O molecules in the nanopores of a beryl crystal-lattice and observe a rich and highly anisotropic set of absorption lines in the terahertz spectral range. Two bands can be identified, which originate from translational and librational motions of the water molecule isolated within the cage; they correspond to the analogous broad bands in liquid water and ice. In the present case of well-defined and highly symmetric nanocavities, the observed fine structure can be explained by macroscopic tunneling of the H 2 O molecules within a six-fold potential caused by the interaction of the molecule with the cavity walls.
Crystallography Reports, 2009
A formula for the propagation velocity of the regeneration surface front is derived under the ass... more A formula for the propagation velocity of the regeneration surface front is derived under the assumption of equal growth rates of the polyhedral crystal faces and the corresponding faces forming subindividuals of the regeneration surface. It is shown that both sharp minima (increase of the face) and sharp maxima (decrease of the face) can correspond to faces in the growth rate diagram. An experimental diagram of the growth rates of the [110] zone of potash alum crystals is constructed which confirms the analytical conclusions. It is established that the regeneration surface growth rate decreases with time. This effect is caused by the disappearance of rapidly growing faces from subindividual faceting. The faceting of a regenerating crystal changes in the direction of successive disappearance of sharp maxima in the growth rate diagram.
Crystallography Reports, 2009
A formula for the propagation velocity of the regeneration surface front is derived under the ass... more A formula for the propagation velocity of the regeneration surface front is derived under the assumption of equal growth rates of the polyhedral crystal faces and the corresponding faces forming subindividuals of the regeneration surface. It is shown that both sharp minima (increase of the face) and sharp maxima (decrease of the face) can correspond to faces in the growth
Journal of Infrared, Millimeter, and Terahertz Waves, 2018
Petrology, 2014
In order to determine the mechanisms of formation and properties of natural hydrosilicate liquids... more In order to determine the mechanisms of formation and properties of natural hydrosilicate liquids (HSLs), which are formed during the transition from magmatic to hydrothermal mineral formation in gra nitic pegmatites and rare metal granites, the formation of HSLs was experimentally studied in the
Journal of Structural Chemistry, 2004
The contents of the structural channels of beryl, grown hydrothermally from an ammonium-containin... more The contents of the structural channels of beryl, grown hydrothermally from an ammonium-containing solution, were investigated by IR and EPR spectroscopy. Using IR spectroscopy we found that water molecules, ammonium ions, and a small number of HCl molecules enter the structural channels of beryl in the course of mineral growth. In these beryls, the ammonium ions play the role of alkali cations. The ammonium ions are as rigidly fixed in the lattice as are water molecules; they are eliminated by calcination at high temperatures close to the decomposition temperature. On exposure to radiation at 77 K, the paramagnetic 3 NH and H 0 radicals are stabilized in the structural channels of beryl. In addition to the known H 0 radical, other states of atomic hydrogen, interacting with medium protons, are observed as well. For one of the additional radicals, H b , we suggest the model of atomic hydrogen stabilized at the center of a silicon-oxygen ring with two water molecules in adjacent cavities.
Journal of Crystal Growth, 1999
ABSTRACT
Applied Magnetic Resonance, 2005
CrystEngComm
This study explores the fine structural details of the boundaries between the growth micro-sector... more This study explores the fine structural details of the boundaries between the growth micro-sectors in a ruby crystal grown hydrothermally on a nonsingularly oriented (011̄2̄) seed.
Crystal Growth & Design
A quantitative analysis of the evolution of a spherical surface artificially prepared from a pota... more A quantitative analysis of the evolution of a spherical surface artificially prepared from a potassium alum single-crystal during its regeneration is carried out in real growth experiments. The results are compared with the results of the numerical simulation based on the proposed regeneration process kinematical model. It is demonstrated that for many boundary conditions there is a close quantitative correspondence between the model and real experiments on the regeneration of single-crystal balls. It is shown that the most important parameter that has a quantitative effect on the growing regeneration surface evolution is the geometry of the roughness (protrusions and depressions), initially present on this surface. The rare quantitative discrepancies between the results of real growth and numerical experiments are due to the discrepancies between the geometry of the roughness set in the model and those actually present on the regenerating single-crystal ball. The proximity of the model to real regenerati...
Journal of Infrared, Millimeter, and Terahertz Waves
CrystEngComm
This study explores the fine structural details of the boundaries between the growth micro-sector... more This study explores the fine structural details of the boundaries between the growth micro-sectors in a leucosapphire (pure corundum, α-Al2O3) crystal grown hydrothermally on a nonsingularly oriented (01-1-2) seed. Numerous...
Crystal Growth & Design, 2016
Journal of Solid State Chemistry, Dec 1, 1998
Phase Transitions, 2014
When water is confined to nanocavities, its quantum mechanical behavior can be revealed by terahe... more When water is confined to nanocavities, its quantum mechanical behavior can be revealed by terahertz spectroscopy. We place H 2 O molecules in the nanopores of a beryl crystal lattice and observe a rich and highly anisotropic set of absorption lines in the terahertz spectral range. Two bands can be identified, which originate from translational and librational motions of the water molecule isolated within the cage; they correspond to the analogous broad bands in liquid water and ice. In the present case of well-defined and highly symmetric nanocavities, the observed fine structure can be explained by macroscopic tunneling of the H 2 O molecules within a six-fold potential caused by the interaction of the molecule with the cavity walls.
When water is confined to nanocavities, its quantum mechanical behavior can be revealed by terahe... more When water is confined to nanocavities, its quantum mechanical behavior can be revealed by terahertz spectroscopy. We place H 2 O molecules in the nanopores of a beryl crystal lattice and observe a rich and highly anisotropic set of absorption lines in the terahertz spectral range. Two bands can be identified, which originate from translational and librational motions of the water molecule isolated within the cage; they correspond to the analogous broad bands in liquid water and ice. In the present case of well-defined and highly symmetric nanocavities, the observed fine structure can be explained by macroscopic tunneling of the H 2 O molecules within a six-fold potential caused by the interaction of the molecule with the cavity walls.
The Journal of chemical physics, Jan 14, 2014
Low-energy excitations of a single water molecule are studied when confined within a nano-size ca... more Low-energy excitations of a single water molecule are studied when confined within a nano-size cavity formed by the ionic crystal lattice. Optical spectra are measured of manganese doped beryl single crystal Mn:Be3Al2Si6O18, that contains water molecules individually isolated in 0.51 nm diameter voids within the crystal lattice. Two types of orientation are distinguished: water-I molecules have their dipole moments aligned perpendicular to the c axis and dipole moments of water-II molecules are parallel to the c-axis. The optical conductivity σ(ν) and permittivity ɛ'(ν) spectra are recorded in terahertz and infrared ranges, at frequencies from several wavenumbers up to ν = 7000 cm(-1), at temperatures 5-300 K and for two polarizations, when the electric vector E of the radiation is parallel and perpendicular to the c-axis. Comparative experiments on as-grown and on dehydrated samples allow to identify the spectra of σ(ν) and ɛ'(ν) caused exclusively by water molecules. In th...
Journal of Physics: Conference Series, 2014
ABSTRACT
The Journal of Physical Chemistry Letters, 2013
When water is confined to nanocavities, its quantum-mechanical behavior can be revealed by terahe... more When water is confined to nanocavities, its quantum-mechanical behavior can be revealed by terahertz spectroscopy. We place H 2 O molecules in the nanopores of a beryl crystal-lattice and observe a rich and highly anisotropic set of absorption lines in the terahertz spectral range. Two bands can be identified, which originate from translational and librational motions of the water molecule isolated within the cage; they correspond to the analogous broad bands in liquid water and ice. In the present case of well-defined and highly symmetric nanocavities, the observed fine structure can be explained by macroscopic tunneling of the H 2 O molecules within a six-fold potential caused by the interaction of the molecule with the cavity walls.
Crystallography Reports, 2009
A formula for the propagation velocity of the regeneration surface front is derived under the ass... more A formula for the propagation velocity of the regeneration surface front is derived under the assumption of equal growth rates of the polyhedral crystal faces and the corresponding faces forming subindividuals of the regeneration surface. It is shown that both sharp minima (increase of the face) and sharp maxima (decrease of the face) can correspond to faces in the growth rate diagram. An experimental diagram of the growth rates of the [110] zone of potash alum crystals is constructed which confirms the analytical conclusions. It is established that the regeneration surface growth rate decreases with time. This effect is caused by the disappearance of rapidly growing faces from subindividual faceting. The faceting of a regenerating crystal changes in the direction of successive disappearance of sharp maxima in the growth rate diagram.
Crystallography Reports, 2009
A formula for the propagation velocity of the regeneration surface front is derived under the ass... more A formula for the propagation velocity of the regeneration surface front is derived under the assumption of equal growth rates of the polyhedral crystal faces and the corresponding faces forming subindividuals of the regeneration surface. It is shown that both sharp minima (increase of the face) and sharp maxima (decrease of the face) can correspond to faces in the growth