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21.
Hartree-Fock clusters calculations were performed of cross luminescence (CRL) in CdF2. Results are compared with earlier results on BaF2. Alternative calculations were done on levels and transition rates using a band structure model. From a comparison of the two cases a possible explanation is given of the fact that CRL in CdF2, presumably in the visible wavelength region, is difficult to detect. 相似文献
22.
The excitation and emission properties of the lanthanides Ce3+, Pr3+, Nd3+, Sm3+, Eu3+, Tb3+, Er3+, Tm3+, and Yb3+ in LiYP4O12 were studied by vacuum ultra-violet spectroscopy at 10 K. It provides information on the energies of 4f-5d excitation and emission bands. In the case of Er3+ spin forbidden emission was observed. Charge transfer excitation bands were identified for Eu3+, Sm3+, Tm3+, and Yb3+, and in the case of Yb3+ charge transfer luminescence is observed. All data appear to be consistent with each other and have been used to construct a level scheme showing the location of the energy levels of all trivalent and divalent lanthanides in LiYP4O12. 相似文献
23.
Ki Hwan Bae 《中国化学快报》2009,20(11):1321-1323
Phytochemical study on the BuOH-soluble fraction of the stem bark of Populus davidiana resulted in the isolation of a new salicin derivative(1),named davidianoside.The structure was elucidated on the basis of extensive physicochemical and spectroscopic analyses. 相似文献
24.
From the transport studies in the bilayer manganites LaSr2−x
Ca
x
Mn2O7, we have found the variable-range hopping model proposed by Viret et al to be inadequate to describe the transport of charge in these materials. The polarons appear to hop to their nearest neighbors
with an activation energy, which in part is dependent on the magnetic interactions in the lattice. 相似文献
25.
26.
The spectroscopic properties of R1/2Na1/2TiO3:Pr3+ (R=La, Gd, Y, Lu) are investigated in the temperature range 77-500 K and interpreted in the frame of the intervalence charge transfer (IVCT) model. The model allowed locating the ground state of Pr3+ relative to the host fundamental bands with an accuracy of 0.1-0.2 eV. 相似文献
27.
The broad bands in the room-temperature excitation spectra of Sm3+-, Dy3+- and Tm3+-activated Ca-α-SiAlON phosphors are interpreted as the N3−-to-rare earth charge transfer transition (CTT). From the energies of the charge transfer transitions and from the optical data presented for the Eu2+ ion, the location of the divalent rare earth ion energy levels relative to the valence and the conduction band of Ca-α-SiAlON is derived. The salient features of the energy-level diagram are shown to be practical in explaining the temperature-dependent variations of the Eu2+ and Yb2+ luminescence efficiency in Ca-α-SiAlON. A comparative study pertaining to the nature of the Yb2+ and Eu2+ ion luminescence in Ca-α-SiAlON and in SrSi2O2N2 is presented. A tentative energy-level diagram of the trivalent rare earth ions in Ca-α-SiAlON is also constructed. 相似文献
28.
MVN Murthy Urjit A Yajnik KRS Balaji G Bhattacharyya Amol Dighe Shashikant Dugad ND Hari Dass PK Kabir Kamales Kar D Indumathi John G Learned Debasish Majumdar NK Mondal MVN Murthy SN Nayak Sandip Pakvasa Amitava Raychaudhuri RS Raghavan G Rajasekaran R Ramachandran Alak K Ray Asim K Ray Saurabh Rindani HS Sharatchandra Rahul Sinha Nita Sinha S Umasankar Urjit A Yajnik 《Pramana》2000,55(1-2):347-355
We have identified some important and worthwhile physics opportunities with a possible neutrino detector located in India.
Particular emphasis is placed on the geographical advantage with a stress on the complimentary aspects with respect to other
neutrino detectors already in operation. 相似文献
29.
S Chanda Sarmishtha Bhattacharyya Tumpa Bhattacharjee SS Ghugre Swapan Kumar Basu S Muralithar RP Singh B Mukherjee RK Bhowmik SN Ray 《Pramana》2001,57(1):175-179
The high spin states in N=80 139Pr have been investigated by in-beam γ-spectroscopic techniques following the reaction 130Te (14N, 5n) reaction at E=75 MeV, using a gamma detector array, consisting of seven 23% compton-suppressed high purity germanium detectors and a multiplicity
ball of fourteen bismuth germanate elements. Based on γ-γ coincidence data, the level scheme of 139Pr has been considerably extended up to 7.2 MeV excitation. Tentative spin-parity assignments are done for the newly proposed
levels on the basis of the DCO ratios corresponding to strong gates and the available information from the earlier light ion
experiments. 相似文献
30.
Sodium dialkyl phosphite reacts with non-activated alkyl halide in the presence of crown ether to give dialkyl alkyl phosphonate in moderate yield. Little or no reaction takes place in the absence of crown ether under the same conditions. In all cases, crown ether was present in catalytic amts. indicating that it behaves as a phase transfer catalyst between solid and liquid phases. The influences of structures of crown ethers, alkyl halides, dialkyl phosphites and the nature of solvent on the P-alkylation of sodium dialkyl phosphite have been investigated. 相似文献