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1.
I.A. Godunov N.N. Yakovlev S.I. Bokarev A.V. Abramenkov D.V. Maslov 《Journal of Molecular Spectroscopy》2009,255(1):39-44
The vapor-phase absorption spectrum of oxalyl chloride in the 3000-4180 Å region has been re-examined at high resolution. Singlet-singlet and singlet-triplet electronic transitions of the trans-conformer found in the spectrum are in agreement with earlier works [W.J. Balfour, G.W. King, J. Mol. Spectrosc. 26 (1968) 384-397; ibid. 27 (1968) 432-442]. Torsion levels of trans-oxalyl chloride in the ground and excited and states were found for the first time. Ab initio calculations of structures for conformers of oxalyl chloride in the ground and lowest excited electronic states explain the absence of second conformer transitions in the vibronic absorption spectrum. 相似文献
2.
Yujie Liang Baoqing Zeng Yangyang Song Jing Huang Te Li 《Solid State Communications》2011,151(9):704-707
nanostructures were synthesized by using different Bi sources via a simple solvothermal process, in which and BiCl3 were used as the Bi sources. Optical properties of nanostructures prepared with and BiCl3 as the Bi sources were investigated by micro-Raman spectroscopy. The Raman scattering spectrum of hexagonal nanoplates prepared by using as the Bi source shows that the infrared (IR) active mode A1u, which must be odd parity and is Raman forbidden for bulk crystal due to its inversion symmetry, is greatly activated and shows up clearly in the Raman scattering spectrum. We attribute the appearance of the infrared active A1u mode in the Raman spectrum to crystal symmetry breaking of hexagonal nanoplates. However, the Raman scattering spectrum of nanostructures with irregular shape prepared by using as the Bi source only exhibits the two characteristic Raman modes of crystals. Micro-Raman measurements on nanostructures with different morphologies offer us a potential way to tailor optical properties of nanostructures by controlling the morphologies of the nanostructures, which is very important for practical applications of nanostructures in thermoelectric devices. 相似文献
3.
Using the ab initio Hartree-Fock crystal orbital method in its linear combination of atomic orbitals form we have calculated the band structures of poly(-) and poly(-). Here, besides the nucleotide bases, the sugar and phosphate parts of the nucleotide were also taken into account together with their first water shell and Na+ ions. We use the notation with a tilde above the abbreviation of a base for the whole nucleotide; for instance poly() means a guanine base with the deoxyribose and PO4− groups to which it is bound. The obtained band structures were compared with previous single chain calculations as well as with the earlier poly(-) and poly(-) calculation without water but in the presence of counterions. One finds that all the bands of poly(-) and poly(-) are shifted considerably upwards as compared to the previous single chain results (poly(), poly(), poly() and poly()). This effect is explained by the ∼0.2e charge transfer from the sugars of both chains to the nucleotide bases. The fundamental gaps between the nucleotide base-type highest filled and lowest unfilled bands are decreased in both cases by 1-3 eV, because the valence bands are purine-type and the conduction bands pyrimidine-type, respectively, while in the case of single homopolynucleotides they belong to the same base. We also pointed out that the LUMO is mainly Na+-like in both investigated cases and several unoccupied bands (belonging to the Na+ ions, the phosphate group and the water molecules) can be found between this and the first unoccupied pyrimidine-like empty band. 相似文献
4.
The recent observation at the Tevatron of (uub and ddb) baryons within 2 MeV of the predicted Σb-Λb splitting and of baryons at the Tevatron within a few mega electron volts (MeV) of predictions has provided strong confirmation for a theoretical approach based on modeling the color hyperfine interaction. The prediction of = 5790-5800 MeV is reviewed and similar methods used to predict the masses of the excited states and . The main source of uncertainty is the method used to estimate the mass difference mb-mc from known hadrons. We verify that corrections due to the details of the interquark potential and to Ξb- mixing are small. For S-wave qqb states we predict , and . For states with one unit of orbital angular momentum between the b quark and the two light quarks we predict , and . Results are compared with those of other recent approaches. 相似文献
5.
I.A. Godunov N.N. Yakovlev D.V. Maslov S.I. Bokarev 《Journal of Molecular Spectroscopy》2010,260(2):124-129
The gas phase absorption spectrum of oxalyl fluoride in the region of 37 000–29 300 cm−1 has been examined at high resolution. Singlet–singlet and singlet–triplet electronic transitions of the trans-conformer were found in the spectrum. The fundamental frequencies of trans-oxalyl fluoride in the and electronic states were determined.In the low resolution ultraviolet absorption spectrum of oxalyl fluoride in the gas phase the transition of the cis-conformer (νmax) was found to be shifted to the blue by about 6000 cm−1 relative to the transition of the trans-conformer. 相似文献
6.
The Kondo insulator Y bB12 is known to undergo a transition to the metallic state with doping or under an external magnetic field. Within the virtual crystal approximation (VCA), we calculated the occupation of the Yb 4f and 5d shells, and , as a function of doping of Y bB12 with the rare earths Tm and Lu. We found that exhibits an anomalous change at the critical concentration of the dopant, in agreement with experiment ( for Y b1−xLuxB12 and for Y b1−xTmxB12). We suggest that the critical behaviour seems to be strictly connected with the change of and in consequence the change of the Yb valency. 相似文献
7.
Brian J. Drouin Shanshan Yu Holger S.P. Müller Frank Lewen Hideta Habara 《Journal of Quantitative Spectroscopy & Radiative Transfer》2010,111(9):1167-1173
High precision rotational spectra of isotopic oxygen O2 (with or ) in its electronic ground state have been measured in selected frequency regions between 0.4 and 2.0 THz. The main isotopic species, , was also investigated in its first excited electronic state . The new data, analyzed together with previous measurements, yielded improved spectroscopic parameters. 相似文献
8.
Inelastic neutrino scattering cross sections for the even-even Mo isotopes (contents of the MOON detector at Japan), at low and intermediate electron neutrino energies (?i≤100 MeV), are calculated. MOON is a next-generation double beta and neutrino-less double-beta-decay experiment which is also a promising facility for low-energy neutrino detection. The nuclear wave functions required in this work have been constructed in the context of the quasi-particle random phase approximation (QRPA) and the results presented refer to , , , and isotopes. 相似文献
9.
A class of highly fluorescent and stable carbazole end-capped phenylene ethynylene compounds have been synthesized and characterized. They show high extinction coefficients of absorption () and quantum yields of fluorescence (; ΦF=0.52-0.73) in dichloromethane. The solid state absorptions and emissions are significantly red-shifted from the dilute solution ones (; ). Their photoluminescent properties and crystal structures have been investigated with the aim of providing a basis for elucidating the structure-physical property relationships. These data indicate their potential use as blue-emitting materials in organic light-emitting diodes (OLEDs). 相似文献
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D.B. Sinars S.A. Pikuz T.A. Shelkovenko K.M. Chandler D.A. Hammer J.P. Apruzese 《Journal of Quantitative Spectroscopy & Radiative Transfer》2003,78(1):61-83
Time-resolved spectroscopic measurements of the radiation emitted from Al, Ti, and Mo X pinches have been made with time resolution. The radiation is emitted from micropinch plasmas with sizes of order in times in the 10- range. Spectra implied that dense, plasmas were produced, such as a lifetime, 1.5- electron temperature and near solid-density Ti plasma. The experimental systems and analysis methods are described in detail, including line ratio calculations for μm-scale Ti and Al plasmas with ion densities of 1019-1024 cm−3 and electron temperatures. 相似文献
12.
We have irradiated SrTiO3 single crystal with 3 MeV-proton (H+) beam and found that blue -, green - and infrared - frequency photoluminescence (PL) are induced simultaneously at room temperature. TEM and EELS analyses show that an oxygen-deficient amorphous layer is formed at the crystal surface by the proton irradiation. Possible origin of the PL-effect is discussed. 相似文献
13.
Niharika Mohapatra Sitikantha D. Das K. Mukherjee 《Solid State Communications》2011,151(19):1340-1343
The magnetic entropy change (), a measure of the magnetocaloric effect, in Tb5Si3, a compound exhibiting unusual positive magnetoresistance following a magnetic-field-induced transition below the magnetic transition temperature (∼69 K), has been investigated. We found that is negative in the paramagnetic state. At the magnetic transition temperature, shows a sign reversal from a negative value (in the paramagnetic state) to a positive value (in the magnetically ordered state). The high-field state, which is interestingly the high resistive state, is found to be associated with higher entropy, i.e., large positive , behaving like a paramagnet. On the basis of this observation, we conclude that the magnetic field induces magnetic fluctuations in the system resulting in positive magnetoresistance, thereby rendering support to the idea of inverse metamagnetism in this compound. In addition, we note that the Arrott plots present an interesting scenario. 相似文献
14.
Formation of muonic molecules and , where J is rotational quantum number, in electron conversion process is investigated at collision energies between 0.004 eV and 50 eV. Corresponding reaction rates are calculated in adiabatic approximation for the three-body Coulomb problem. Significant enhancement of the rates for and is found near 7 eV and 30 eV, respectively. It is shown that the enhancement is due to resonances present in elastic and scattering at these energies. Acceleration of dμ atoms up to the resonant energy could be realized in triple H-D-3He mixture due to the muon transfer from protium to deuterium. Experimental investigation of nuclear synthesis from molecular state directly formed in the mixture is suggested. 相似文献
15.
I.R. Shein 《Solid State Communications》2011,151(17):1165-1168
The tetragonal (s.g. I4/mmm; #139) ThCr2Si2 is widely known as a structural type of the broad family of the so-called 122-like ternary phases which includes now more than 800 members. Among them the superconducting iron-pnictides (discovered in 2008, -earth metals) and the newest superconducting iron-chalcogenides (discovered in 2010, metals) have attracted recently enormous interest in this class of materials. Meanwhile, the data about the electronic, magnetic, and elastic properties of the ThCr2Si2 phase itself are still practically absent. Here, by means of first-principles calculations, the optimized structural parameters, spin ordering of the magnetic ground state, independent elastic constants, bulk, shear, and Young’s moduli, elastic anisotropy indexes, total and partial densities of states, and inter-atomic bonding picture for ThCr2Si2 were obtained for the first time and analyzed in comparison with the aforementioned most popular 122-like systems and . 相似文献
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P. VingerhoetsK.T. Flanagan J. BillowesM.L. Bissell K. BlaumB. Cheal M. De RydtD.H. Forest Ch. GeppertM. Honma M. KowalskaJ. Krämer K. KreimA. Krieger R. NeugartG. Neyens W. Nörtershäuser J. PapugaT.J. Procter M.M. RajabaliR. Sánchez H.H. StrokeD.T. Yordanov 《Physics letters. [Part B]》2011,703(1):34-39
18.
A Monte Carlo simulation has been used to study the magnetic properties and the critical behaviors of a single spherical nanoparticle, consisting of a ferromagnetic core of spins surrounded by a ferromagnetic shell of S=±1, 0 or , spins with antiferromagnetic interface coupling, located on a simple cubic lattice. A number of characteristic phenomena has been found. In particular, the effects of the shell coupling and the interface coupling on both the critical and compensation temperatures are investigated. We have found that, for appropriate values of the system parameters, two compensation temperatures may occur in the present system. 相似文献
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By considering a simple thermodynamic system, in thermal equilibrium at a temperature T and in the presence of an external parameter A, we focus our attention on the particular thermodynamic (macroscopic) relation . Using standard axioms from information theory and the fact that the microscopic energy levels depend upon the external parameter A, we show that all usual results of statistical mechanics for reversible processes follow straightforwardly, without invoking the Maximum Entropy principle. For the simple system considered herein, two distinct forms of heat contributions appear naturally in the Clausius definition of entropy, . We give a special attention to the amount of heat , associated with an infinitesimal variation at fixed temperature, for which a “generalized heat capacity”, , may be defined. The usefulness of these results is illustrated by considering some simple thermodynamic cycles. 相似文献