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971.
Min Cheng 《辐射效应与固体损伤》2013,168(11-12):1083-1089
ABSTRACTThe EPR g factors g// and g⊥ for the tetragonal (CrO4)3? impurity center in ZrSiO4: Cr5+ crystal are studied from the high-order perturbation formulas based on the two-mechanism (the crystal field and charge-transfer mechanisms) model. The studies indicate that differing from the tetragonally-elongated host (SiO4)4- tetrahedron, the dominant defect structure of the substitutional (CrO4)3? tetrahedron is tetragonally- compressed with the ground state |dz2 due to the Jahn-Teller distortion. Furthermore, the agreement of g factors between calculation and experiment requires a small admixture of the first excited state |dx2?y2 to the ground state |dz2 due to the vibrational motion of ligands, which leads a compressed (CrO4)3? tetrahedron to become a twinkling elongated one, These results are discussed. 相似文献
972.
Serena Indelicato David Bongiorno Sergio Indelicato Laszlo Drahos Vincenzo Turco Liveri Lilla Turiák Karoly Vékey Leopoldo Ceraulo 《Journal of mass spectrometry : JMS》2013,48(3):379-383
The characteristic collision energy (CCE) to obtain 50% fragmentation of positively and negatively single charged noncovalent clusters has been measured. CCE was found to increase linearly with the degrees of freedom (DoF) of the precursor ion, analogously to that observed for synthetic polymers. This suggests that fragmentation behavior (e.g. energy randomization) in covalent molecules and clusters are similar. Analysis of the slope of CCE with molecular size (DoF) indicates that activation energy of fragmentation of these clusters (loss of a monomer unit) is similar to that of the lowest energy fragmentation of protonated leucine–enkephalin. Positively and negatively charged aggregates behave similarly, but the slope of the CCE versus DoF plot is steeper for positive ions, suggesting that these are more stable than their negative counterparts. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
973.
《Analytical letters》2012,45(7):1397-1412
Abstract Silicon nitride membrane ISFET sensor chips have been produced with varying gate dimensions. A series of width/length (W/L) aspect ratios have been examined, combined with three levels of boron ion-implant. The level of ion-implantation affects the threshold voltage; this is important as a low threshold voltage allows the use of low noise operating conditions. Gate dimensions are also important factors for they determine the level of drain current for a given gate and drain voltages. A novel design feature, aimed at achieving wide gates, is the use of folded gates as well as having a straight structure. The evaluation of devices with gates covered with poly(vinyl chloride) (PVC)-valinomycin-dioctyl adipate was based on their response to potassium chloride standards when it was shown that there may be a maximum width of gate above which there is no improvement of response. Also, the effect of folding the gate structure is discussed and shown to be tenable, thus permitting greater miniaturisation. 相似文献
974.
Milovan M. Stoiljković Igor A. Pašti Miloš D. Momčilović Jelena J. Savović Mirjana S. Pavlović 《Spectrochimica Acta Part B: Atomic Spectroscopy》2010
Enhancement of emission line intensities by induced oscillations of direct current (DC) arc plasma with continuous aerosol sample supply was investigated using multivariate statistics. Principal component analysis (PCA) was employed to evaluate enhancements of 34 atomic spectral lines belonging to 33 elements and 35 ionic spectral lines belonging to 23 elements. Correlation and classification of the elements were done not only by a single property such as the first ionization energy, but also by considering other relevant parameters. Special attention was paid to the influence of the oxide bond strength in an attempt to clarify/predict the enhancement effect. Energies of vaporization, atomization, and excitation were also considered in the analysis. In the case of atomic lines, the best correlation between the enhancements and first ionization energies was obtained as a negative correlation, with weak consistency in grouping of elements in score plots. Conversely, in the case of ionic lines, the best correlation of the enhancements with the sum of the first ionization energies and oxide bond energies was obtained as a positive correlation, with four distinctive groups of elements. The role of the gas-phase atom-oxide bond energy in the entire enhancement effect is underlined. 相似文献
975.
Laibin Zhang Huifang Li Jilai Li Xiaohua Chen Yuxiang Bu 《Journal of computational chemistry》2010,31(4):825-836
A comprehensive theoretical study of electronic transitions of naphtho‐homologated base analogs, namely, yy‐T , yy‐C , yy‐A , and yy‐G , was performed. The nature of the low‐lying excited states is discussed, and the results are compared with those from experiment and also with those of y‐bases. Geometrical characteristics of the lowest excited singlet ππ* and nπ* states were explored using the CIS method, and the effects of methanol solution and paring with their complementary natural bases on the relevant absorption and emission spectra of these modified bases were examined. The calculated excitation and emission energies agree well with the measured data, where experimental results are available. In methanol solution, the fluorescence from yy‐A and yy‐G would be expected to occur around 539 and 562 nm, respectively, suggesting that yy‐A is a green‐colored fluorophore, whereas yy‐G is a yellow‐colored fluorophore. The methanol solution was found to red‐shift both the absorption and emission maxima of yy‐A , yy‐T , and yy‐C , but blue‐shift those for yy‐G . Generally, though base pairing has no significant effects on the absorption and fluorescence maxima of yy‐A , yy‐C , and yy‐T , it blue‐shifts those for yy‐G . © 2009 Wiley Periodicals, Inc. J Comput Chem 2010 相似文献
976.
The experimental one-, three-, and five-quasiparticle bands in ~(177)Lu are analyzed by the particle-number conserving (PNC) method for treating the cranked shell model with pairing interaction, in which the blocking effects are taken into account exactly. The experimental moments of inertia are reproduced very well by PNC calculations with us free parameter. 相似文献
977.
Measurement systems capability analysis aims to test if the variability of a measurement system is small relative to the variability of a monitored process. At present some open questions are related both to the interpretation of the critical values of the indices typically used by practitioners to assess the capability of a gauge and to the choice of the size of the experimental design to test the repeatability and the reproducibility of the measurement process. In this paper, starting from the misclassification rates of a measurement system, we present a solution to these issues. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
978.
This study aims at quantifying the nano-size effect in terms of elastic and thermal properties in nano-reinforced polymers. Nano-reinforced PMMA with 4% volume fraction of silica nanoparticles was prepared using particle diameters of 15 nm, 25 nm, 60 nm, 150 nm and 500 nm. Uniaxial tensile tests showed an increase in Young's modulus with decreasing particle diameter when the volume fraction was kept constant. This increase is the signature of the nano-size effect on the macroscopic mechanical properties. Conversely to mechanical properties, the presence of particles in the matrix induced a decrease in glass transition, possibly due to weak interactions between the matrix and silica nanoparticles. 相似文献
979.
We study paraxial beam propagation along the wedge axis of a disclinated amorphous medium. The defect-induced inhomogeneity results in Berry phase and curvature that are affected by the induced uniaxial anisotropy. The Berry phase manifests itself as a precession of the polarization vector. The Berry curvature is responsible for the optical spin Hall effect in the disclinated medium, where beam deflection varies sinusoidally along the paraxial direction. Its application in determining the birefringence and the magnitude of the Frank vector is explained. 相似文献
980.
The propagation characteristics of the longitudinal wave in a piezoelectric nanoplate were investigated in this study. The nonlocal elasticity theory was used and the surface effects were taken into account. In addition, the group velocity and phase velocity were derived and investigated, respectively. The dispersion relation was analyzed with different scale coefficients, wavenumbers, and voltages. The results showed that the dispersion degree can be strengthened by increasing the wavenumber and scale coefficient. 相似文献