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1.
Tanner PA Ning L Makhov VN Khaidukov NM Kirm M 《The journal of physical chemistry. B》2006,110(24):12113-12118
Excitation of the 4f3 ion Nd3+ in hexafluoroelpasolite lattices by synchrotron radiation of wavelength approximately 185 nm leads to fast 4f(2)5d --> 4f3 emission below 52,630 cm(-1) and slower 4f3 --> 4f3 emission from the luminescent states (4)F(3/2) gamma8u (11 524 cm(-1)) and 2G2(9/2) gamma8u (approximately 47,500 cm(-1)). The near-infrared emission is well-resolved, and a clear interpretation of the 4I(9/2) crystal field levels and of the one-phonon vibronic sideband is given. The excitation spectrum of the 2G2(9/2) emission enables clarification of the structure of the 4f(2)5d configuration (which extends from approximately 52,000 to 128,000 cm(-1)). Detailed energy level and intensity calculations have been performed, which provide simulations of the d-f emission and the f-d excitation spectra in good agreement with experiment. It is interesting that although the 4f3 2G2(9/2) gamma8u --> 4f3 4I(J) transitions are very weak in intensity compared with transitions terminating upon higher multiplet terms, most of the 4f(2)5d (3H) 4I(9/2) gamma8g --> 4f3 emission intensity resides in the transitions to 4I(J). 相似文献
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Makhov DV Popović DM Stuchebrukhov AA 《The journal of physical chemistry. B》2006,110(24):12162-12166
The protonation state of His291 in cytochrome c oxidase (CcO), a ligand to the Cu(B) center of the enzyme, has been recently studied in this group by using combined density functional theory (DFT)/electrostatic (QM/MM) calculations. On the basis of these calculations, a model of the proton pumping mechanism of CcO has been proposed. Due to certain technical difficulties, the procedure used in the previous calculation to find partial atomic charges of the QM system for the solvation energy evaluation was not entirely satisfactory; i.e., it was not self-consistent. Here, we describe a procedure that resolves the problem and report on the improved calculations of the protonation state of the His residue. The new procedure fits the protein and reaction field potentials in the region of the QM system with artificial point charges placed on a surface of a sphere surrounding the QM system and a few charges inside the sphere and allows one to perform DFT calculations that involve an inhomogeneous dielectric environment in a self-consistent way. The procedure improves the accuracy of calculations in comparison with previous work. The improved results show, however, that although the absolute energies change significantly the relative energies of the protonated and deprotonated states of His291 remain close to the previously reported ones and therefore do not change significantly the pK(a) values reported earlier. Therefore, our new improved calculations support for the proposed His291 model of the CcO pump. 相似文献
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Measurement of electrodynamic parameters of superconducting films in the far-infrared and submillimeter frequency ranges 总被引:1,自引:0,他引:1
B. P. Gorshunov G. V. Kozlov A. A. Volkov S. P. Lebedev I. V. Fedorov A. M. Prokhorov V. I. Makhov J. Schützmann K. F. Renk 《International Journal of Infrared and Millimeter Waves》1993,14(3):683-702
Possibilities of determing the complex conductivity of thin super-conducting films using far-infrared and submillimeter reflectivity and transmissivity techniques are discussed. It is shown that within the framework of standard approaches a satisfactory accuracy is available only for the imaginary part of the conductivity (dielectric permittivity). Different resonator methods are suggested for measuring the real part of the conductivity. Data for superconducting NbN films at frequencies 3 – 25 cm–1 are presented. 相似文献
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V.N. Makhov M. Kirm G. Stryganyuk S. Vielhauer G. Zimmerer B.Z. Malkin O.V. Solovyev S.L. Korableva 《Journal of luminescence》2012,132(2):418-424
The emission and excitation spectra as well as decay kinetics of luminescence due to 5d–4f transitions in Ce3+, Gd3+ and Lu3+ ions doped into LiCaAlF6 crystals have been analyzed with high spectral and time resolution using synchrotron radiation for excitation. The rich fine structure originating from electronic origins of transitions and their phonon replica has been well resolved and identified. Experimental data are compared with the spectra simulated in the framework of the semiphenomenological models of the crystal field and the crystal lattice dynamics. 相似文献
6.
The reflection spectra in the fundamental-absorption region, 5–25 eV (250–40 nm), of optically active crystals with cubic
symmetry (NaClO3, NaBrO3) and uniaxial optically active crystal (LiIO3) have been investigated. It is shown that the reflection spectra of cubic crystals have a similar structure, which is determined
by the electronic transitions in the XO3 group. The comparison of these spectra with the corresponding spectrum of lithium iodide made it possible to determine the
type of transition in the spectra of cubic crystals. Using the projection operator method, it was shown that the sign of optical
rotation of cubic crystals with symmetry T is independent of the screw axis sign. Possible reasons for the unprecedentedy large optical rotation of lithium iodide crystal
in the optical axis direction are considered. 相似文献
7.
V.V. Harutunyan T.S. Hakobyan V.A. Gevorkyan V.N. Makhov 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,12(1):31-33
The excitation spectra of luminescence in irradiated and nonirradiated corundum crystals are investigated by means of highly
polarised synchrotron radiation in 5 to 30 eV region. In the fundamental absorption region the double-exciton peaks are observed
in the region 8.5-9.2 eV for irradiated (especially by neutrons) crystals at temperature 90 K. At 9.5 eV sharp drops appeared,
in the luminescence spectrum space which were interpreted as nonirradiative near-surface recombination, the probability of
which sharply increased at high absorption coefficients. The enhancement of the luminescence efficiency in the high-energy
region was connected with the decay effect of electron excitations as well as with the influence of volumetric excitations
leading to the enhancement of recombination glow.
Received 16 October 1998 and Received in final form 20 January 1999 相似文献
8.
Stage of electron transfer between p-phenylenediamines and chloranil in methanol was studied and a strictly reversible redox conversion of reagents was observed at low temperatures of ?50 to ?90°C. At positive temperatures, the proton transfer initiates a polycondensation yielding a polyaminoquinone of brown color. The nature of the absorption bands of charge-transfer complexes in the visible spectral range is discussed. Quantum-chemical calculations of excited reaction complexes and of absorption spectra of polyaminoquinone were performed. 相似文献
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