相关论文: Luminescence of alpha-quartz
Electrons and holes can spontaneously form excitons and condense in a semimetal or semiconductor, as predicted decades ago. This type of Bose condensation can happen at much higher temperatures in comparison with dilute atomic gases.…
In this study, the optical response to a terahertz pulse was investigated in the transition metal chalcogenide Ta$_2$NiSe$_5$, a candidate excitonic insulator. First, by irradiating a terahertz pulse with a relatively weak electric field…
Journal ref.: J. Phys.: Condens. Matter 25, 065602 (2013): We investigated the optical reflectivity of the heavy-fermion metal CeCu2Si2 in the energy range 3 meV - 30 eV for temperatures between 4K - 300K. The results for the charge…
We present a reanalysis of the HeII Lyman alpha absorption towards the quasars HS1700+6416 and HE2347-4342 using new high S/N, optical observations. An alternative analysis method is applied, which fits the high quality, optical HI data…
A new excitation is observed at 201 meV in the doped-hole ladder cuprate Sr$_{14}$Cu$_{24}$O$_{41}$, using ultraviolet resonance Raman scattering with incident light at 3.7 eV polarized along the direction of the rungs. The excitation is…
Hafnia-based nanostructures and other high-k dielectrics are promising wide-gap materials for developing new opto- and nanoelectronics devices. They possess a unique combination of physical and chemical properties such as insensitivity to…
We report resonant X-ray scattering measurements on the orbitally-degenerate triangular metallic antiferromagnet 2H-AgNiO2 to probe the spontaneous transition to a triple-cell superstructure at temperatures below 365 K. We observe a strong…
We have investigated the exciton dynamics in transition metal dichalcogenide mono-layers using time-resolved photoluminescence experiments performed with optimized time-resolution. For MoSe2 monolayers, we measure $\tau_{rad}=1.8\pm0.2$ ps…
The redshifted 1420 MHz emission from the HI in unresolved damped Lyman-\alpha clouds at high z will appear as a background radiation in low frequency radio observations. This holds the possibility of a new tool for studying the universe at…
Lead and tin-based chalcogenide semiconductors like PbTe or SnSe have long been known to exhibit an unusually low thermal conductivity that makes them very attractive thermoelectric materials. An apparently unrelated fact is that the…
We present spectral energy distributions (SEDs) of 69 QSOs at z>5, covering a rest frame wavelength range of 0.1mu to ~80mu, and centered on new Spitzer and Herschel observations. The detection rate of the QSOs with Spitzer is very high…
The blazar Mrk 501 (z=0.034) was observed at very-high-energy (VHE, $E\gtrsim 100$~GeV) gamma-ray wavelengths during a bright flare on the night of 2014 June 23-24 (MJD 56832) with the H.E.S.S. phase-II array of Cherenkov telescopes. Data…
Al(110) has been studied for temperatures up to 900 K via ensemble density-functional molecular dynamics. The strong anharmonicity displayed by this surface results in a negative coefficient of thermal expansion, where the first interlayer…
The optical properties of the heavy-fermion compound UPd$_2$Al$_3$ have been measured in the frequency range from 0.04 meV to 5 meV (0.3 to 40 cm$^{-1}$) at temperatures $2 {\rm K}<T< 300$ K. Below the coherence temperature $T^*\approx 50$…
The luminescence of fifteen representative Eu$^{2+}$-doped phosphors used for white-LED and scintillation applications is studied through a Constrained Density Functional Theory. Transition energies and Stokes shift are deduced from…
We have observed the BL Lac object 1ES2344+514 (z = 0.044) in Very High Energy (VHE) gamma-ray and near-infrared wavelength bands with TACTIC and MIRO telescopes respectively. The observations were made from 18th October to 9th December…
A model is suggested to explain the frequently observed presence of intense, narrow-band, H(alpha) emission lines in the optical spectra of reddened, early-type stars (e.g. HD 44179, IRAS 18179-1346, IRAS 20298+4011). It is proposed that…
Excitons are promising candidates for generating superfluidity and Bose-Einstein Condensation (BEC) in solid state devices, but an enabling material platform with in-built bandstructure advantages and scaling compatibility with industrial…
Layered materials enable the assembly of a new class of heterostructures where lattice-matching is no longer a requirement. Interfaces in these heterostructures therefore become a fertile ground for unexplored physics as dissimilar…
We have carried out $^{125}$Te nuclear magnetic resonance (NMR) in a wide temperature range of 1.5 -- 300 K to investigate electronic properties of Ge$_{50}$Te$_{50}$, Ag$_{2}$Ge$_{48}$Te$_{50}$ and Sb$_{2}$Ge$_{48}$Te$_{50}$ from a…