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941.
The nature of the lowest triplet configuration of flavins 总被引:1,自引:0,他引:1
Abstract— The phosphorescence spectrum of riboflavin has been reexamined at 77°K in an ethylene glycol: water matrix. The phosphorescence occurs at approximately the 605 nm (ca. 2-·05 eV) region, in reasonable agreement with the theoretical calculations of 1·6–1·8 eV [21]. The emission was found to be negatively polarized, and to have a relatively long lifetime (0·56 sec). On the basis of this data and additional theoretical results, it is concluded that the lowest triplet of riboflavin is of 3(τ,τ*) type. Upon addition of potassium iodide, the phosphorescence emission is enhanced through spin-orbit perturbation. The presence of oxygen (atmospheric pressure) in the frozen glass apparently has no effect on the emission. The phosphorescence spectra of alloxazine are also presented. Results of the present work have been applied to the photodephosphorylation of menadiol diphosphate in elucidating its mechan ism involving the riboflavin triplet and singlet oxygen. 相似文献
942.
L.T. Yang J.K. Liang G.B. Song J. Luo F.S. Liu H.F. Yang G.H. Rao 《Applied Physics A: Materials Science & Processing》2005,80(4):865-870
The compound FeSr2NdCu2O7+ (Fe1212) was successfully synthesized by solid-state reaction. X-ray diffraction data indicate that the sample is of single phase. Rietveld whole-pattern-fitting method was used to refine the crystal structure of samples prepared under different annealing conditions using the tetragonal system with space group P4/mmm. Magnetization measurements indicate that magnetic susceptibility changes with temperature in a Curie-type manner. Resistance measurements indicate that these samples have a semiconductor-like behavior. PACS 61.10.Nz; 74.72.Jt 相似文献
943.
X.H. Liu M.H. Hong W.D. Song G.X. Chen H.M.J. Lam J.P. Wang T C. Chong 《Applied Physics A: Materials Science & Processing》2005,80(3):611-614
Barium ferrite (BaFe12O19) thin films have been deposited by pulsed laser deposition (PLD) on Si substrates with MgO underlayers. The films were deposited in oxygen atmosphere by excimer laser (=248 nm, pulse duration=23 ns) in the temperature range 750–900 °C. The experiments showed that the substrate temperature has remarkable effect on the films magnetic and structural properties. The BaFe12O19 films deposited at 900 °C in 200 mTorr oxygen showed some perpendicular orientation, with a perpendicular squareness of 0.5 and an in-plane squareness of 0.3. Such thin BaFe12O19 films have platelet grains with a size of about 300 nm. The perpendicular saturation magnetization and coercivity are 185 emu/cm3 and 1.4 kOe, respectively. PACS 81.15.Fg.; 75.70.Ak; 75.50.Pp; 68.55.j 相似文献
944.
Y.Z. Peng W.D. Song C.W. An J.J. Qiu J.F. Chong B.C. Lim M.H. Hong T. Liew T.C. Chong 《Applied Physics A: Materials Science & Processing》2005,81(3):565-568
Diluted magnetic semiconductor Co-doped ZnO film has been synthesized by a dual beam pulsed laser deposition method. The magnetic, electrical, and optical properties of the Zn0.985Co0.015O0.67 film are studied in this paper. The film shows ferromagnetic behavior with a coercivity of about 300 Oe at room temperature, and semiconductor behavior with carrier concentration of 2.2×1018 cm-3, and a resistivity of 102 mcm. Structural investigations indicated that the film has similar lattice constants to that of ZnO. It is shown that the film exhibits excellent optical properties with a band gap energy of 3.31 eV, which is close to that of ZnO. The origins of the magnetism are also discussed. PACS 81.15.Fg; 75.50 Pp; 61.72.Vv 相似文献
945.
Zilan L Xiaodong H Ke C Ruijuan N Xuhui L Xiaoping Z Tongjun Y Bei Z Song C Zhijian Y Zhizhong C Guoyi Z 《Micron (Oxford, England : 1993)》2005,36(3):281-284
Laser lift-off (LLO) technology is successfully used to prepare GaN-based TEM cross-sectional specimens. Detailed procedures of the method to prepare the specimens are demonstrated. Large thin areas suitable for TEM analysis were obtained. TEM images of the resulting GaN interface are studied, and the changes in structural quality are confined to approximately the first 250 nm of the epilayer. Clear TEM images of the whole epilayer and the InGaN quantum wells and the HRTEM images of the superlattice layer are demonstrated, showing that LLO is a quick and ideal method to study the crystal structure of the epilayer, especially if only the upper layers are of interest. 相似文献
946.
We present a one-scan method for determining fluid flow velocity within a few milliseconds in the presence of a static field gradient, and without the need of multiple scans. A few RF-pulses populate a series of coherence pathways, each of which exhibits a phase shift that is proportional to fluid velocity. These coherence pathways produce spin echoes separated in the time domain, thus eliminating the need for phase cycling. 相似文献
947.
Choi HC Bae SY Jang WS Park J Song HJ Shin HJ Jung H Ahn JP 《The journal of physical chemistry. B》2005,109(5):1683-1688
Nitrogen (N)-doped carbon nanotubes (CNTs) were heated to 1000 degrees C under an ultrahigh vacuum. X-ray photoelectron spectroscopy (XPS) and X-ray absorption near-edge structure (XANES) reveal three different N structures; graphitelike, pyridine-like, and molecular N(2). The vibrationally resolved XANES peaks of N(2) were first observed, suggesting the existence of molecular N(2) as intercalated and trapped forms. The annealing process can decrease the average N content from 6.3 at. % to 3.3 at. %, mainly by releasing molecular N(2). Electron energy-loss spectroscopy (EELS) confirms that the annealing releases molecular N(2) from the CNTs. 相似文献
948.
Thin films of polyelectrolyte/J aggregate dye bilayers with high absorption coefficient (6 nm thick with alpha approximately equal to 1.0 x 10(6) cm(-1)) inserted in an optical microcavity enable the cavity quantum electrodynamic strong coupling limit to be reached at room temperature with a coupling strength (Rabi splitting) of 265 +/- 15 meV. By embedding these films in a resonant cavity organic LED structure, we demonstrate the first emissive electrically pumped exciton-polariton device. 相似文献
949.
Yan-Qing?GuoEmail author Ling?Zhou He-Shan?Song 《International Journal of Theoretical Physics》2005,44(9):1373-1382
A method of perturbative expansion of master equation is employed to study the dissipative properties of system and of atom
in the two-photon Jaynes–Cummings model (JCM) with degenerate atomic levels. The numerical results show that the degeneracy
of atomic levels prolongs the period of entanglement between the atom and the field. The asymptotic value of atomic linear
entropy is apparently increased by the degeneration. The amplitude of local entanglement and disentanglement is suppressed.
The better the initial coherence property of the degenerate atom, the larger the coherence loss. 相似文献
950.
To read out correct data from shift-multiplexed holographic data storage, we propose a novel method of pixel matching by use of a tiny plane-parallel refraction plate placed in the path of converging readout beams. Tilting the refraction plate produces a shift in the lateral position of the readout beam incident upon the holographic storage disk, leading to compensation for pixel-mismatch errors by an improvement in bit-error rate of 3 orders of magnitude. 相似文献