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181.
Sushil K. Misra S. I. Andronenko A. Punnoose Dmitry Tipikin J. H. Freed 《Applied magnetic resonance》2009,36(2-4):291-295
High-frequency (236 GHz) electron paramagnetic resonance (EPR) studies of Fe3+ ions at 255 K are reported in a Sn1?x Fe x O2 powder with x = 0.005, which is a ferromagnetic semiconductor at room temperature. The observed EPR spectrum can be simulated reasonably well as the overlap of spectra due to four magnetically inequivalent high-spin (HS) Fe3+ ions (S = 5/2). The spectrum intensity is calculated, using the overlap I(BL) + (I(HS1) + I(HS2) + I(HS3) + I(HS4)) × exp(?0.00001B), where B is the magnetic field intensity in Gauss, I represents the intensity of an EPR line (HS1, HS2, HS3, HS4), and BL stands for the baseline (the exponential factor, as found by fitting to the experimental spectrum, is related to the Boltzmann population distribution of energy levels at 255 K, which is the temperature of the sample in the spectrometer). These high-frequency EPR results are significantly different from those at X-band. The large values of the zero-field splitting parameter (D) observed here for the four centers at the high frequency of 236 GHz are beyond the capability of X-band, which can only record spectra of ions with much smaller D values than those reported here. 相似文献
182.
Nanoscale laser processing and diagnostics 总被引:2,自引:0,他引:2
David Hwang Sang-Gil Ryu Nipun Misra Hojeong Jeon Costas P. Grigoropoulos 《Applied Physics A: Materials Science & Processing》2009,96(2):289-306
The article summarizes research activities of the Laser Thermal Laboratory on pulsed nanosecond and femtosecond laser-based
processing of materials and diagnostics at the nanoscale using optical-near-field processing. Both apertureless and apertured
near-field probes can deliver highly confined irradiation at sufficiently high intensities to impart morphological and structural
changes in materials at the nanometric level. Processing examples include nanoscale selective subtractive (ablation), additive
(chemical vapor deposition), crystallization, and electric, magnetic activation. In the context of nanoscale diagnostics,
optical-near-field-ablation-induced plasma emission was utilized for chemical species analysis by laser-induced breakdown
spectroscopy. Furthermore, optical-near-field irradiation greatly improved sensitivity and reliability of electrical conductance
atomic force microscopy enabling characterization of electron tunneling through the oxide shell on silicon nanowires. Efficient
in-situ monitoring greatly benefits optical-near-field processing. Due to close proximity of the probe tip with respect to
the sample under processing, frequent degradation of the probe end occurs leading to unstable processing conditions. Optical-fiber-based
probes have been coupled to a dual-beam (scanning electron microscopy and focused ion beam) system in order to achieve in-situ
monitoring and probe repair. 相似文献
183.
A. Dwivedi S. A. Siddiqui O. Prasad L. Sinhal N. Misra 《Journal of Applied Spectroscopy》2009,76(5):623-629
The molecular geometry and vibrational frequencies of 5-phenyl-2-(4-pyridyl)pyrimidine in the ground state have been calculated
by the density functional theory with B3LYP/6-311G(d) as the basis set. The observed frequencies of 5-phenyl-2-(4-pyridyl)pyrimidine
and those calculated are nearly the same. The form of the modes for all fundamentals is based on potential energy distribution
calculations. 相似文献
184.
185.
Let T be any tree of order d≥1. We prove that every connected graph G with minimum degree d contains a subtree T′ isomorphic to T such that G−V(T′) is connected. 相似文献
186.
187.
An efficient stereoselective dihydroxylation of glycals using a bimetallic system, RuCl3/CeCl3/NaIO4 总被引:2,自引:0,他引:2
A catalytic dihydroxylation reaction on glycals has been developed using a bimetallic oxidizing system to furnish sugar 1,2-diols in a highly stereoselective manner. 相似文献
188.
We study the nonlinear propagation of dust-ion acoustic (DIA) shock waves in an un-magnetized dusty plasma which consists of electrons, both positive and negative ions and negatively charged immobile dust grains. Starting from a set of hydrodynamic equations with the ion thermal pressures and ion kinematic viscosities included, and using a standard reductive perturbation method, the Kadomtsev-Petviashivili-Burgers (K-P-Burgers) equation is derived, which governs the evolution of DIA shocks. A stationary solution of the K-P-Burgers equation is obtained and its properties are analysed with different plasma number densities, ion temperatures and masses. It is shown that a transition from shocks with negative potential to positive one occurs depending on the negative ion concentration in the plasma and the obliqueness of propagation of DIA waves. 相似文献
189.
The collective excitation of surface plasmons in a massless Dirac plasma (e.g., graphene) half-space (bounded by air) is investigated using a relativistic quantum fluid model. The unique features of such surface waves are discussed and compared with those in a Fermi plasma. It is found that in contrast to Fermi plasmas, the long-wavelength surface plasmon frequency (ω) in massless Dirac plasmas is explicitly nonclassical, i.e., , where is the Planck's constant. Besides some apparent similarities between the surface plasmon frequencies in massless Dirac plasmas and Fermi plasmas, several notable differences are also found and discussed. Our findings elucidate the properties of surface plasmons that may propagate in degenerate plasmas where the relativistic and quantum effects play a vital role. 相似文献
190.
The dielectric relaxation mechanism in five heterocyclic compounds in dilute solutions using microwave technique is reported.
Measurements have been made at different temperatures in order to calculate dipole moments and free energies of activation
for the process of dipole orientation and viscous flow. It has been observed that the relaxation time is very closely related
with the molecular parameters, such as size, shape and nature of the solute molecule. 相似文献