The Experts below are selected from a list of 231 Experts worldwide ranked by ideXlab platform
Georg Zimmerer - One of the best experts on this subject based on the ideXlab platform.
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Excitons in Rare-Gas solids: Exotic or model-like?
Journal of Luminescence, 2006Co-Authors: Georg ZimmererAbstract:Abstract Key results of spectroscopic experiments on excitons in Rare-Gas solids performed during the last three decades are summarized. They show that excitons in Rare-Gas solids have some unique properties due to peculiarities of the solids, like absence of acoustic phonons or huge band gap energies. On the other hand, excitons in Rare-Gas solids turn out to be textbook models for excitons in systems with strong exciton–lattice interaction. The substantial progress in Rare-Gas exciton spectroscopy was mainly due to the fact that synchrotron radiation was used as the light source, in particular for luminescence experiments. Due to some peculiar properties, excitons in Rare-Gas solids can serve as probes for electron–electron scattering and complex elementary excitations.
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SURFACE RELAXATIONS OF SELECTIVELY EXCITED Rare-Gas DOPED Rare-Gas SOLIDS
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 1996Co-Authors: M. Runne, Georg ZimmererAbstract:Abstract Surface relaxations of selectively excited Rare-Gas doped Rare-Gas solids include desorption of excited atoms and the formation of atomic 3P1 and 3P2-type surface centers as well as of homonuclear and heteronuclear molecular centers. Time-resolved luminescence spectra originating from these centers indicate that the long-living 3P2-type centers act as reservoirs for the formation of the molecular type centers.
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Relaxation of selectively excited atoms at the surface of Rare-Gas doped Rare-Gas solids
Journal of Electron Spectroscopy and Related Phenomena, 1996Co-Authors: M. Runne, B. Peters, Georg ZimmererAbstract:Abstract Following primary selective 3 P 1 type excitation of Rare-Gas guest atoms at the surface of Rare-Gas host crystals two relaxation channels are observed, (i) the desorption of electronically excited guest atoms, and (ii) the radiative decay of weakly bound atomic 3 P 1 and 3 P 2 type and of molecular-type surface centers. The desorption of excited atoms is ascribed to the ‘cavity-ejection mechanism’. The emitting atomic-type centers consist of guest atoms in an ‘on-top’ geometry. Measurements have been performed on all systems with positive V 0 values.
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Exciton spectroscopy of Rare-Gas solids and of Rare-Gas clusters
International Conference on Excitonic Processes in Condensed Matter, 1995Co-Authors: Malte Joppien, Dirk Varding, Georg Zimmerer, Thomas MoellerAbstract:ABSTRACT Highlights concerning the creation and the decay dynamics of excitons in Rare-Gas solids and in solid Rare-Gas clusters will be presented. The decay dynamics include exciton transport, exciton trapping and exciton-induced desorption. Pronounced quantum-size effects are observed in Rare-Gas clusters. Recent experimental results on electronic excitations incondensed He, obtained from liquid He-clusters in a supersonic beam will be included. 1. INTRODUCTIONSince about three decades, the electronic and especially the excitonic properties of Rare-Gas solids (RGS) are underinvestigation, and the enormous amount of information already availabe has been documented in several reviews' Rare-Gas excitons have large oscillator strengths and show up at the onset of optical absorption as pronounced absorption lines. A collection of absorption data5 (imaginary part of the dielectric function) in the range ofvalence excitations is given in Fig. 1. As animmediate consequence of the closed-shell electronic configuration
Markku Räsänen - One of the best experts on this subject based on the ideXlab platform.
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chemical compounds formed from diacetylene and Rare Gas atoms hkrc4h and hxec4h
Journal of the American Chemical Society, 2003Co-Authors: Hanna Tanskanen, Leonid Khriachtchev, Jan Lundell, Harri Kiljunen, Markku RäsänenAbstract:New organic Rare-Gas compounds, HRgC4H (Rg = Kr or Xe), are identified in matrix-isolation experiments supported by ab initio calculations. These compounds are the largest molecules among the known Rare-Gas hydrides. They are prepared in low-temperature Rare-Gas matrixes via UV photolysis of diacetylene and subsequent thermal mobilization of H atoms at ∼30 and 45 K for Kr and Xe, respectively. The strongest IR absorption bands of the HRgC4H molecules are the H−Rg stretches with the most intense components at 1290 cm-1 for HKrC4H and at 1532 cm-1 for HXeC4H, and a number of weaker absorptions (C−H stretching, C−C−C bending, and C−C−H bending modes) are also found in agreement with the theoretical predictions. As probably the most important result, the IR absorption spectra indicate some further stabilization of the HRgC4H molecules as compared with the corresponding HRgC2H species identified recently (Khriachtchev et al. J. Am. Chem. Soc. 2003, 125, 4696 and Khriachtchev et al. J. Am. Chem. Soc. 2003, 125,...
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New Rare-Gas-Containing Neutral Molecules
European Journal of Inorganic Chemistry, 1999Co-Authors: Mika Pettersson, Jan Lundell, Markku RäsänenAbstract:The synthesis of novel neutral Rare-Gas-containing molecules of type HXY, where × = Xe or Kr and Y is an electronegative atom or fragment, is discussed. The molecules are characterised experimentally by their vibrational spectra and computationally by extensive ab initio calculations. They are formed in low-temperature Rare-Gas solids from neutral reagents and their bonding consists of both covalent and ionic contributions. Our recent studies add to the previously known class of Rare-Gas chemical bonds in neutral ground-state molecules the new bonds Xe–H, Xe–I, Xe–Br, Xe–S, Kr–H, Kr–C, and Kr–Cl.
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NOVEL Rare Gas CHEMISTRY
1997Co-Authors: Markku Räsänen, Mika Pettersson, Jan Lundell, Leonid KhriachtchevAbstract:References: Neutral Rare-Gas containing charge-transfer molecules in solid matrices. I. HXeCl, HXeBr, HXel and HKrCl in Kr and Xe. M.Pettersson, J.Lundell, M.R\""as\""anen, {J.Chem.Phys}. 102 (1995) 6423-31. Neutral Rare Gas containing charge-transfer molecules in solid matrices. II. HXeH, HXeD and DXeD in Xe. M.Pettersson, J.Lundell, M.R\""as\""anen, {J.Chem.Phys}. 103 (1995) 205-10. The mechanism of formation and IR-induced decomposition of HXel in solid Xe. M.Pettersson, J.Nieminen, L.Khriachtchev, M.R\""as\""anen, {J.Chem.Phys. to be submitted}.
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neutral Rare Gas containing charge transfer molecules in solid matrices i hxecl hxebr hxei and hkrcl in kr and xe
Journal of Chemical Physics, 1995Co-Authors: Mika Pettersson, Jan Lundell, Markku RäsänenAbstract:Ultraviolet‐irradiation of hydrogen halide containing Rare Gas matrices yields the formation of linear centrosymmetric cations of type (XHX)+, (X=Ar, Kr, Xe). Annealing of the irradiated doped solids produces, along with thermoluminescence, extremely strong absorptions in the 1700–1000 cm−1 region. Based on isotopic substitution and halogen dependence of these bands, the presence of hydrogen and halogen atom(s) in these species is evident. In the present paper we show the participation of Rare Gas atom(s) in these new compounds. The evidence is based on studies of the thermally generated species in mixed Rare Gas matrices. The new species are assigned as neutral charge‐transfer molecules HX+Y− (Y=halogen), and their vibrational spectra are discussed and compared with those calculated with ab initio methods. This is the first time hydrogen and a Rare Gas atom has been found to make a chemical bond in a neutral stable compound. The highest level ab initio calculations on the existence of compounds of type HXY corroborate the experimental observations. The mechanism responsible for the formation of these species is also discussed.
Franck Rabilloud - One of the best experts on this subject based on the ideXlab platform.
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Effects of Rare-Gas Matrices on the Optical Response of Silver Nanoclusters
Journal of Physical Chemistry C, 2018Co-Authors: R. Schira, Franck RabilloudAbstract:The optical response of silver clusters, Agn with n = 8, 20, 35, 58, 92, embedded in a Rare-Gas matrix are calculated in the framework of the Time-Dependent Density Functional Theory (TDDFT). We present a methodology able to reproduce with unprecedented accuracy the experimental spectra measured on metal clusters embedded in neon, argon, krypton and xenon solid matrices. In our approach, the metal cluster is surrounded by explicit Rare-Gas atoms and embedded in a polarizable continuum medium. Interactions with the surrounding medium affects both the position and the width of the surface plasmon absorption band of metal clusters. The size dependent shift of the surface plasmon band is evaluated in the case of a neon matrix. While the band shifts to lower energies (red shift) for large clusters, it shifts to higher energies (blue shift) for very small clusters.
Janmichael Rost - One of the best experts on this subject based on the ideXlab platform.
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small Rare Gas clusters in soft x ray pulses
Physical Review Letters, 2004Co-Authors: Christian Siedschlag, Janmichael RostAbstract:We develop a microscopic model for the interaction of small Rare-Gas clusters with soft x-ray radiation from a free electron laser. It is shown that, while the overall charging of the clusters is rather low, unexpectedly high atomic charge states can arise due to charge imbalances inside the cluster. These findings are explained by an increased absorption via inverse bremsstrahlung due to high intermediate charge states and by a nonhomogenous charge distribution inside the cluster.
Donald G. Truhlar - One of the best experts on this subject based on the ideXlab platform.
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Comparative DFT Study of van der Waals Complexes: Rare-Gas Dimers, Alkaline-Earth Dimers, Zinc Dimer, and Zinc-Rare-Gas Dimers
The journal of physical chemistry. A, 2006Co-Authors: Yan Zhao, Donald G. TruhlarAbstract:Recent interest in the application of density functional theory prompted us to test various functionals for the van der Waals interactions in the Rare-Gas dimers, the alkaline-earth metal dimers, zinc dimer, and zinc-Rare-Gas dimers. In the present study, we report such tests for 18 DFT functionals, including both some very recent functionals and some well-established older ones. We draw the following conclusions based on the mean errors in binding energies and complex geometries: (1) B97-1 gives the best performance for predicting the geometry of Rare-Gas dimers, whereas M05-2X and B97-1 give the best energetics for Rare-Gas dimers. (2) PWB6K gives the best performance for the prediction of the geometry of the alkaline-earth metal dimers, zinc dimers, and zinc-Rare-Gas dimers. M05-2X gives the best energetics for the metal dimers, whereas B97-1 gives the best energetics for the zinc-Rare-Gas dimers. (3) The M05 functional is unique in providing good accuracy for both covalent transition-metal dimers and van der Waals metal dimers. (4) The combined mean percentage unsigned error in geometries and energetics shows that M05-2X and MPWB1K are the overall best methods for the prediction of van der Waals interactions in metal and Rare-Gas van der Waals dimers.
