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1.
Sharmistha Dutta Choudhury 《Journal of luminescence》2007,124(1):33-38
Laser flash photolysis of phenazine (PZ) solution reveals the existence of a stable species with a long lifetime at 380 nm in addition to the usual triplet PZ at 440 nm. The former is suggested to be due to formation of triplet PZ excimer. The triplet excimer also undergoes photoinduced electron transfer with some aromatic amines. The formation of PZ dimer anion radical and amine cation radicals are confirmed by external magnetic field effect studies. Measurement of B1/2, which estimates hyperfine present in the system, also supports this assignment. 相似文献
2.
An expeditious synthesis of aryl substituted E‐homoallylic bromides has been accomplished by the cleavage of cyclopropylcarbinols with phosphorus tribromide. 相似文献
3.
4.
Organic halides absorbed without solvent onto sodium phenylsulfinate on alumina (1) gave phenylsulfones (2) under microwave or ultrasound activation. 相似文献
5.
Smruti Dash Kaushik Ghoshal T. R. G. Kutty 《Journal of Thermal Analysis and Calorimetry》2013,112(1):179-185
Uranium–zirconium, uranium niobium, and uranium–zirconium–niobium alloys were synthesized by the arc melting technique and their phase transition temperatures were determined using a high temperature calorimeter. Heat capacities of U–7 wt%Zr, U–7 wt%Nb, U–5 wt%Zr–2 wt%Nb, U–3.5 wt%Nb–3.5 wt%Zr, and U–2 wt%Zr–5 wt%Nb were measured using a differential scanning calorimeter in the temperature range 303–921 K. A set of self-consistent thermodynamic functions such as entropy, enthalpy, and Gibbs energy function data for these binary and ternary alloys were reported for the first time using heat capacity data obtained in this study and required literature data. 相似文献
6.
7.
Sharmistha Pal B. N. Roopa Khalid Abu Sulur G. Manjunath Sudhir Nambiar 《Journal of Thermal Analysis and Calorimetry》2014,115(3):2261-2268
Thermal techniques, differential scanning calorimetry (DSC), and hot stage microscopy (HSM) have been used to study the interactions between furosemide and caffeine that are known to form a 1:1 cocrystal. This system has been used as an example to study the probable mechanism of cocrystal formation when the individual components, which are polymorphic, are heated. The study indicates that the phase transition of the low temperature stable polymorph of furosemide initiates cocrystal formation. This result suggests increased mass transfer rate can trigger cocrystal formation. The binary phase diagram (composition–temperature plots) of furosemide–cocrystal–caffeine system was determined from the DSC curves. The results imply that the cocrystal forms eutectic with caffeine but not with furosemide. This study has thus exemplified the use of DSC in understanding binary phase system where the two components form a cocrystal. 相似文献
8.
Sharmistha Karmakar Dr. Ayan Datta 《Angewandte Chemie (International ed. in English)》2014,53(36):9587-9591
At room temperature, 1,2‐hydrogen‐transfer reactions of N‐heterocyclic carbenes, like the imidazol‐2‐ylidene to give imidazole is shown to occurr almost entirely (>90 %) by quantum mechanical tunneling (QMT). At 60 K in an Ar matrix, for the 2, 3‐dihydrothiazol‐2‐ylidene→thiazole transformation, QMT is shown to increase the rate about 105 times. Calculations including small‐curvature tunneling show that the barrier for intermolecular 1,2‐hydrogen‐transfer reaction is small, and QMT leads to a reduced rate of the forward reaction because of nonclassical reflections even at room temperature. A small barrier also leads to smaller kinetic isotope effects because of efficient QMT by both H and D. QMT does not always lead to faster reactions or larger KIE values, particularly when the barrier is small. 相似文献
9.
Summary We study the effective electron mass at the Fermi level in Kane-type semiconductors on the basis of fourth order in effective
mass theory and taking into account the interactions of the conduction electrons, heavy holes, light holes and split-off holes,
respectively. The results obtained are then compared to those derived on the basis of the well-known three-band Kane model.
It is found, takingn-Hg1−x
Cd
x
Te as an example, that the effective electron mass at the Fermi level in accordance with fourth-order model depends on the
Fermi energy, magnetic quantum number and the electron spin respectively due to the influence of band nonparabolicity only.
The dependence of effective mass on electron spin is due to spin-orbit splitting parameter of the valence band in three-band
Kane model and the Fermi energy due to band nonparabolicity in two-band Kane model. The same mass exhibits an oscillatory
magnetic-field dependence for all the band models as expected since the origin of oscillations in the effective mass in nonparabolic
compounds is the same as that of the Shubnikov-de Hass oscillations. In addition, the corresponding results for parabolic
energy bands have been obtained from the generalized expressions under certain limiting conditions. 相似文献
10.
Numerical solution of a system of coupled non-linear integro-differential equations of Fredholm type
A method, based on a generalization of Runge-Kutta's method, is applied to a system of coupled integro-differenital equations of Fredholm type. It is shown that, under certain conditions, the related integral, containing an unknown variable, in each integro-differential equation can be approximated by a contraction operator, converging in the respective space concerned. Therefore they may be found by the method of iteration, starting from arbitrary values, and hence the given system may be solved, with a high degree of accuracy. 相似文献