Search results for "Absorption"
showing 10 items of 2701 documents
Theoretical absorption spectrum of the Ar–CO van der Waals complex
2003
The three-dimensional intermolecular electric dipole moment surface of Ar–CO is calculated at the coupled cluster singles and doubles level of theory with the aug-cc-pVTZ basis set extended with a 3s3p2d1f1g set of midbond functions. Using the rovibrational energies and wave functions of our recent study [J. Chem. Phys. 117, 6562 (2002)], temperature-dependent spectral intensities are evaluated and compared to available experimental data. Based on the theoretical spectrum, alternative assignments of the experimentally observed lines in the fundamental band of CO around 2160 and 2166 cm−1 are suggested. Thomas.Bondo@uv.es
Interference-assisted detection of dark photon using atomic transitions
2019
Dark photon is a massive vector particle which couples to the physical photon through the kinetic mixing term. Such particles, if exist, are produced in photon beams and, in particular, in laser radiation. Due to the oscillations between the physical photon and the dark photon, the latter may be, in principle, detected in the light-shining-through-a-wall experiment. We propose a variant of this experiment where the detection of dark photons is based on the atomic transitions. The key feature of this scheme is that the detection probability is first order in the coupling constant due to the interference term in the photon and dark photon absorption amplitudes. We expect that such experiment …
Frequency conversion of propagating surface plasmon polaritons by organic molecules
2008
We demonstrate frequency conversion of surface plasmon polaritons (SPP) by utilizing the coupling between organic dye molecules and SPP. Launching of SPPs into a plasmonic waveguide is done in two ways: by optically excited molecules and by quantum dots (QDs). QDs are demonstrated to overcome the major problem of bleaching occurring with molecules. The SPP propagates tens of micrometers and clear frequency conversion is observed in the SPP spectrum after passing an area of converter molecules. The use of molecules and QDs as elements of all-plasmonic devices has the potential for high integration and use of self-assembly in fabrication. Peer reviewed
Carotenoid bioaccessibility in pulp and fresh juice from carotenoid-rich sweet oranges and mandarins.
2015
Citrus fruits are a good source of carotenoids for the human diet; however, comparative studies of carotenoids in different citrus food matrices are scarce. In this work the concentration and bioaccessibility of carotenoids in sweet oranges and mandarins with marked differences in carotenoid composition were evaluated in pulp and compared to those in fresh juice. The pulp and juice of the red-fleshed Cara Cara sweet orange variety was highly rich in carotenes (mainly lycopene and phytoene) compared to standard Navel orange, while β-cryptoxanthin and phytoene predominated in mandarins. Total carotenoid content in the pulp of the ordinary Navel orange and in the red-fleshed Cara Cara orange, …
A Temperature-Dependent X-Ray Absorption Characterization of Test Filters for the ATHENA Mission X-IFU Instrument
2018
In order to work properly, the X-ray Integral Field Unit of the ATHENA mission requires a set of thermal filters that block the infrared radiation, preventing it to reach the detector. Each filter will be mounted and thermally anchored onto a shield of the multistage cryostat and will be kept at the specific temperature of the stage. On the other hand, the filters partially absorb X-rays, and their transmittance has to be carefully characterized. The effect of temperature on the absorption edges of the elements that make up the filters has not been investigated yet. Here, we report the results of a preliminary run on the optical transmission data around the edges of C, N, and O at different…
Temperature effects on the performances of the ATHENA X-IFU thermal filters
2016
The X-Ray Integral Field Unit (X-IFU) detector on-board ATHENA is an array of TES micro-calorimeters that will operate at ~50 mK. In the current investigated design, five thermal filters (TF) will be mounted on the cryostat shields to attenuate IR radiative load and avoid energy resolution degradation due to photon shot noise. Each filter consists of a thin polyimide film (~50 nm thick) coated with aluminum (~30 nm thick). Since the TF operate at different temperatures in the range 0.05-300 K, it is relevant to study how temperature affects their mechanical/optical performances (e.g. near edge absorption fine structures of the atomic elements in the filter material). Such results are crucia…
X‐irradiation induced photo‐ and thermostimulated luminescence of CsCdF 3 :Mn crystals
2005
Photo- and thermostimulated luminescence (PSL and TSL respectively) of previously X-irradiated CsCdF3 crystal doped with Mn were investigated. After X-irradiation of CsCdF3 crystal at 8 K PSL bands at about 300 nm and 550 nm appear. Several stimulation bands can be revealed for luminescence at 300 nm and 550 nm. The stimulation band at 340 nm is related to an F-type centre absorption band in accordance with the Mollwo-Ivey relation for halide crystals. Subsequent heating of the crystal after X-irradiation at 8 K shows TSL peaks in the temperature regions 8 K – 90 K and 200 K – 300 K. The spectral composition of the TSL involves both bands at 300 nm and 550 nm. Experiments performed allow us…
Radiation defects in undoped and Nd‐doped LaGaO 3 crystals
2005
Radiation induced defects have been studied in undoped and Nd-doped (6 mol% and 12 mol%) LaGaO3 crystals. Wide absorption band (2.2–2.8 eV) was observed after crystal irradiation with X-rays at 300 K. Induced defects have been annealed in air at ∼450 K. Similar absorption band was observed in transient absorption spectra after ns-pulsed electron beam excitation. The radiation defect creation efficiency is higher in undoped LaGaO3 crystal. It is shown that small concentration of Nd-doping increases the LaGaO3 crystal radiation hardness. In transient absorption spectra along with 2.7 eV band the absorption bands at 1.5 eV and 2.2 eV were observed. The decay process of transient absorption has…
<title>Large-scale first-principles calculations of Fe-doped SrTiO<formula><inf><roman>3</roman></inf></formul…
2003
The energy level positions in the optical gap and atomic geometry for the Fe4+ impurity substituting for a host Ti atom in SrTiO3 are calculated using the Unrestricted Hartree-Fock (UHF) method and supercells containing up to 320 atoms. In agreement with experiment, the high spin (S = 2) state is much lower in energy than the zero-spin state. The energy level positions strongly depend on the asymmetric displacements of six nearest O ions which is a combination of the Jahn-Teller and breathing modes. A considerable covalent bonding between the Fe ion and four nearest O ions takes place. We predict a strong dependence of optical absorption energies on the crystal compression or internal tensi…
Photoluminescence excited by ArF and KrF lasers and optical absorption of stishovite mono-crystal
2008
Two photoluminescence bands were found in a stishovite (silicon dioxide) mono-crystal sample under ArF (193 nm) and KrF (248 nm) excitation. The blue band is situated at 3.17 ± 0.02 eV in the case of ArF and at 3 ± 0.2 in the case of KrF. The UV band is at 4.55 ± 0.05 eV in the case of ArF and at 4.5 ± 0.05 eV in the case of KrF. The position of the UV emission band correlates with that excited by x rays. This position is 4.6 ± 0.05 eV with FWHM 0.8 ± 0.05 eV (Truhins et al 2003 Solid State Commun. 127 415). The blue band possesses slow decay kinetics with time constant 16 ± 2 µs and the UV band is fast on the level of 2 ± 0.5 ns, similarly for both lasers. Thermal quenching of both bands b…