Exciton-polaritons in semiconductor microcavities form a highly nonlinear platform to study a variety of effects interfacing optical, condensed matter, quantum and statistical physics. We show that ...the complex polariton patterns generated by picosecond pulses in microcavity wire waveguides can be understood as the Cherenkov radiation emitted by bright polariton solitons, which is enabled by the unique microcavity polariton dispersion, which has momentum intervals with positive and negative group velocities. Unlike in optical fibres and semiconductor waveguides, we observe that the microcavity wire Cherenkov radiation is predominantly emitted with negative group velocity and therefore propagates backwards relative to the propagation direction of the emitting soliton. We have developed a theory of the microcavity wire polariton solitons and of their Cherenkov radiation and conducted a series of experiments, where we have measured polariton-soliton pulse compression, pulse breaking and emission of the backward Cherenkov radiation.
The crystal structure of the rare mineral caryochroite is determined for the first time using X-ray diffractometry and electron microdiffraction data. The new idealized crystal formula of the mineral ...is Na(Sr
0.5
Ca
0.5
)Mg
3
Fe
Mn(
)
10
(Ti
2
Si
12
)O
37
(OH)
14
(Н
2
О)
3
. The parameters of the monoclinic unit cell refined by the least square method are
a
16.550(3),
b
5.281(2),
c
24.25(3) Å, β 93.0°,
Z
= 2, space group
P
2/
n.
The crystal structure of caryochroite is a new type of Ti–Si lattice responsible for the large structural channels, which are able to enclose the exchange cations and a high amount of water components (OH groups and H
2
O molecules).
Native cobalt was found in amphibolite of the Kola superdeep borehole (SG-3) from a depth of 9630 m by a complex of local analytical methods (analytical scanning electron microscopy, electron ...backscatter diffraction). The studied amphibolite is a fine-grained melanocratic rock composed mainly of magnesioferri- hornblende and containing accessory native metal, telluride, sulphotelluride, and sulphide (Au, Ag, Pd, Bi, Cu, Pb, Zn, Sb, and Fe) mineralization.It also includes the clinopyroxene xenoclast carrying a fundamentally different set of accessories—poor in sulphides and including native cobalt. The absence of significant impurities, including iron, in native cobalt and its belonging to the hexagonal α-modification was determined. It is shown, that the metallic cobalt particles exposed during ion polishing of a compact pyroxene matrix cannot be a contaminant, introduced into the sample during drilling and sample preparation. Cobalt, obviously, was formed not only before the stage of retrograde metamorphism and subsequent hydrothermal processing of the amphibolite containing it, but probably long before the formation of the sedimentary protolith of this rock. That is, native cobalt belongs to the early high-temperature mineral phases inherited from the older Proterozoic—Archean main volcanism, while the time of formation of this layer of amphibolites dates back to the age of 2.4 billion years—the Early Karelian era of the Proterozoic.
Palladium mineralization was registered in the Kola superdeep borehole (SG-3) for the first time in samples from deep horizons (in the fault zone at ~10 km). A proper palladium mineral (merenskyite) ...with the formula Pd
1.00
(Te
1.21
Bi
0.79
)
2.00
was detected using the analytical electron microscopy and EBSD methods. The unusually high content of bismuth in the discovered merenskyite crystal most likely indicates the lower temperatures of its formation from a bismuth-rich fluid. This is supported by numerous finds of associated bismuth minerals (native and intermetallic minerals, sulfides, tellurides, and sulfotellurides) as well. A close geochemical association of noble and rare elements was revealed in the composition of the rich and diverse ore mineralization in the samples studied. It can be argued that a new type of mineralization was discovered for the SG-3 rocks: noble metal (Au–Ag–Pd) rare-element (Bi–Te).
A high-calcium high-temperature condensate is detected in the Earth’s impact Lonar crater for the first time. Its finding confirms in practice the theoretical conclusions made earlier from the ...experimental results. The high-silica condensate found in the Lonar crater, which is similar to those ones in the Zhamanshin crater and in the lunar regolith, confirms the absence of a correlation between the compositions of the target and the impact condensates. The presence of high-temperature condensate glasses in ring structures may be one of the diagnostic criteria to differentiate between volcanogenic and impact formations.
For the first time, high-purity native cobalt was detected in two preparations from a lunar regolith sample delivered by the Luna 24 automatic station. Presumably, it was formed during the ...condensation of a substance from an impact gas-plasma cloud. Previously, native cobalt of similar purity was observed only in products of low-temperature hydrothermal alteration of hyperbasites.
For the first time, a high-temperature condensate in the form of two-component glass beads of about 200–400 nm size, consisting of an Al–Ca oxide core rimmed by a uniform oxide film of high-silica ...glass containing iron nano-inclusions, has been found in natural samples of the lunar regolith from Mare Crisium (Luna-24). Earlier, a high-temperature condensate was only theoretically predicted on the basis of laser evaporation experiments.
A 3-µm particle of HgS is found by electron microscopy techniques in studying the lunar regolith samples delivered by Apollo 17. It might have been preserved due to a thin cover of highly siliceous ...glass, having protective functions. This particle was likely formed from a gaseous phase by the condensation of Hg and S vapors.
The results of long-term mineralogical studies of the lunar regolith, obtained using analytical scanning and transmission electron microscopy, are presented. These studies revealed 105 mineral phases ...new for the Moon, 43 of which were discovered for the first time under natural conditions; an electronic link to the final table is given. An example of studying condensate glasses and native molybdenum is presented.
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