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21.
HARUN REŞIT YAZAR 《Pramana》2013,81(4):579-585
The sd-interacting boson approximation (sd-IBA) and the df-interacting boson approximation (df-IBA) can be related to each other and the states of the interacting boson approximation model can be identified with the fully symmetric states in the sdf interacting boson approximation model. A systematic study of the sdf-IBA model showed that the constructed Hamiltonian can successfully describe the strong octupole correlations in the deformed nuclei. We showed that the interacting boson approximation may account for many of these K π ?=?0+ states. It was found that the calculated energy spectra of the gadolinium isotopes agree quite well with the experimental data. The observed B(E2) values were also calculated and compared with the experimental data. 相似文献
22.
This article presents a review of the strategies that have been both demonstrated and proposed for the multiplexing of multiple noninterferometric optical fiber point sensors to form a sensor network. The focus, which avoids consideration of interferometric sensor types, enables discussion of conventional multiplexing tech niques, namely, spatial, time division, frequency division, and wavelength division prior to dealing with combined or hybrid schemes, which exhibit the potential for increased multiplexing gain. Specific advantages and potential drawbacks of the different strategies are provided together with an indication of the number of point sensors that each multiplexing scheme can support. 相似文献
23.
Abstract Recent observation of the acoustic saturation and of phonon echoes in crystalline quartz after light irradiation with fast neutrons indicates that there are the same low-energy atomic tunnelling systems as in Si02 glass. We report measurements of the diffuse X-ray scattering and of the lattice parameter change from neutron irradiated quartz single crystals studying the strength and symmetry of strain defects and their local correlations. For dose 3 × 1018 n/cm2 the diffuse scattering close to the Bragg peaks together with the lattice parameter change shows that the neutrons create defective regions with a volume change of 29 mean atomic volumes. The distortion field of these regions shows no high symmetry. The radius of the heavily strained region is ~ 10 Å. For higher doses the regions grow a little bit but mainly new defective regions are built. According to the various volume fractions of defective regions at various doses the first strong amorphous halo at about K≈ 1.5 A?1 was detected. Since this amorphous scattering is isotropic and during annealing the regions disappear mainly without changing their size we are led to the conclusion that the defective regions are glass-like in nature. So the size of the tunnelling system has to be smaller than 20 Å. 相似文献
24.
Philip S. Hall Graham E. Jackson John R. Moss David A. Thornton Paul F. M. Verhoeven Gareth M. Watkins 《光谱学快报》2013,46(7):1247-1267
Abstract The infrared spectra (4000 - 50 cm?1) of the square planar rhodium(I) complexes cis-[Rh(CO)2 (pyridine) (X)] (X = Cl, Br) and their isotopomers with pyridine-d 5 and 13CO have been determined. Assignments are based on earlier studies on pyridine and its complexes and on the shifts in infrared bands which are caused by the isotopic substitutions employed. Normal coordinate analysis following the procedure of Becher and Mattes has been used to confirm the empirical assignments. The two v(RhC) bands are observed near 490 and 450 cm?1. v(RhN) is found near 210 cm?1 and v(RhX) occurs at 310 (X = Cl) and 235 (X = Br) cm?1. At frequencies below 200 cm?1, the bands are assigned to bending modes in the following sequence: δ (RhN) > δ (CRhC) > δ (RhCl) > γ (RhCl) > γ (RhN). 相似文献
25.
Kaleb C. Burrage Christopher S. Perreault Eric K. Moss Jeffrey S. Pigott Blake T. Sturtevant Jesse S. Smith 《高压研究》2013,33(3):489-498
ABSTRACTThe isothermal compression of transition metal tantalum (Ta) was studied in a diamond anvil cell by X-ray diffraction utilizing rhenium (Re) and gold (Au) as internal X-ray pressure standards. The Re pressure marker was employed during non-hydrostatic compression to pressures up to 310?GPa while the Au pressure marker was used during quasi-hydrostatic compression in a neon pressure-transmitting medium to 80?GPa. Two ultra-high pressure experiments were conducted on Ta and Re mixtures utilizing focused-ion beam machined toroidal diamond anvils with central flats varying from 8 microns to 16 microns in diameter. The Ta metal was observed to be stable in the body-centered-cubic phase to a volume compression V/V0?=?0.581. The measured equations of state (EOS) of Ta using two different calibrations of the Re pressure marker are compared with the ambient temperature isotherm derived from shock compression data. We provide a detailed analysis of EOS fit parameters for Ta under quasi-hydrostatic and non-hydrostatic conditions. 相似文献
26.
27.
Wang J Burdzinski G Kubicki J Platz MS Moss RA Fu X Piotrowiak P Myahkostupov M 《Journal of the American Chemical Society》2006,128(51):16446-16447
Ultrafast photolysis (lambdaex = 270, 350, or 360 nm) of bromophenyl, chlorophenyl, fluorophenyl, and fluoro-para-trifluoromethylphenyl diazirines produces transient species which absorb broadly in the UV and visible regions. Transient decay can be fit to either mono- or biexponential functions (tau1 approximately 0.3-10 ps, tau2 approximately 10-350 ps; dependent on solvent and halogen). Fluoro- and chlorophenylcarbene are formed within the time resolution of the spectrometer (300 fs, 270 nm excitation). Bromophenyl diazirine decay (270 nm excitation) correlates with the growth of bromophenylcarbene. Solvent and substituent effects on the slower decays of the transient absorptions are consistent with assigning the carriers of transient absorption in the visible region to ring-opened zwitterionic species. 相似文献
28.
Fragmentation of (S)-endo-5-norbornenyl-2-oxychlorocarbene [(S)-8] in cyclohexane-d12 gives approximately 20% (S)-endo-2-chloro-5-norbornene [(S)-7] with approximately 50% ee, 65-70% (R)-exo-2-chloro-5-norbornene [(R)-4] with >95% ee, and approximately 12% (R)-3-nortricyclyl chloride [(R)-5] with approximately 22% ee. (Analogous stereochemical results were also obtained starting with the enantiomeric carbene (R)-8.) The (S)-8 to (S)-7 and (S)-8 to (R)-4 conversions are ascribed mainly to retention and inversion S(N)i transition states, respectively. These have been located by computational methods and are nearly isoenergetic. In more polar solvents (CDCl3 and CD3CN), the fragmentation of (S)-8 increasingly occurs via competitive ion pair pathways in which steroselectivity is diminished, and escape to the norbornenyl-nortricyclyl cation directs the products away from endo-2-chloro-5-norbornene toward exo-chloride 4 and nortricyclyl chloride 5. 相似文献
29.
Moss RJ Wadsworth KJ Chapman CJ Frost CG 《Chemical communications (Cambridge, England)》2004,(17):1984-1985
The rhodium catalysed addition of potassium trifluoro(organo)borates to dimethyl itaconate generates an intermediate complex which on protonation provides enantioenriched succinic esters. 相似文献
30.
Lu Z Moss RA Warmuth R Krogh-Jespersen K 《The journal of physical chemistry. A》2011,115(47):13799-13803
Laser flash photolysis of fluorophenyldiazirine incarcerated in hemicarcerand 2 affords incarcerated fluorophenylcarbene [2⊙3], which forms a metastable, innermolecular π-complex with aryl moieties of 2. This carbene complex can be observed spectroscopically. Extensive computational studies provide insights into the structure, spectroscopy, energetics, and kinetics of the 2⊙3 carbene complex. 相似文献