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21.
Bankim Chandra Ghosh 《Molecular physics》2013,111(14):1805-1811
The room-temperature fluorescence of a charge-transfer (CT) complex different from those of the component donor/acceptor in polar organic solvent is not very common. The phenomenon is even rarer in aqueous medium. The present work demonstrates that a CT complex formed between reserpine (Res) and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) in aqueous and aqueous–ethanol media exhibits fluorescence at room temperature that is entirely different from those of the components, Res and DDQ. With decreasing polarity of the medium on the addition of ethanol, the fluorescence intensity and also the fluorimetrically determined formation constant of the complex increase, but the fluorescence emission wavelength does not change significantly. The quantum yield of fluorescence of the CT complex systematically decreases with increasing ethanol content of the medium. That the observed fluorescence is due to the CT complex is established by the constancy of the assumed proportionality constant (β) between the fluorescence intensity and the complex concentration measured using different equilibrium concentrations of the complex and also by demonstrating the mirror image relationship between its excitation and emission spectra in aqueous medium. To our knowledge, this is the first report on the room-temperature fluorescence of a CT complex in aqueous solution. 相似文献
22.
Kaushik Pal Uday Narayan Maiti Tapas Pal Majumder Subhas Chandra Debnath 《Applied Surface Science》2011,258(1):163-168
A series of novel wurtzite cadmium sulphide (CdS) nanowires with uniform diameter were synthesized by using a rapid and simple solvothermal route. CdS nano structures with certain morphology could be selectively produced by only varying the concentration of poly ethylene glycol (PEG) as a surfactant in the reaction system with cadmium acetate, sulphur powder and ethelynediamine (EDA). We extensively studied UV-vis absorption spectra, photoluminescence spectra after confirming CdS nanowires with diameter 24-25 nm and length ranging up to several nano meters by field emission scanning electron microscopy (FE-SEM). Therefore we may definitely propose a new formation mechanism of CdS nanowires assisted by PEG with its illustrating optical properties. 相似文献
23.
This study reports the use of quartz crystal nanobalance (QCN) to study the adsorption of two model molecules namely albumin and doxycycline by hydroxyapatite (HA). The work focuses on the deposition of a stable coating of HA on the quartz crystal, modification of the coating using doxycycline and its subsequent effects on albumin adsorption. The uniformity and thickness of the HA coating has been studied using atomic force microscopy (AFM). The functional groups to ascertain the presence of the selected moieties have been characterized by Raman spectroscopy. The results indicate that the mass of albumin deposited on the surface of the HA coated quartz crystal functionalized with doxycycline shows a substantial increase when compared to the standard HA coated quartz crystal. The adsorbed albumin has also been found to be retained for an enhanced period of time. This surface immobilization of doxycycline and subsequent albumin adsorption seem to be a promising approach to confer biomaterials with antithrombogenic and antibacterial surfaces. 相似文献
24.
Dattatray J. Late Ranjit V. Kashid Chandra Sekhar?Rout Mahendra A. More Dilip S. Joag 《Applied Physics A: Materials Science & Processing》2010,98(4):751-756
Field emission studies of WO2.72 nanowires synthesized by a solvothermal method have been performed in the planar diode configuration under ultra high vacuum
conditions. Fowler–Nordheim plots obtained from the current-voltage characteristics follow the quantum mechanical tunneling
process and a current density of ∼8.3×106 μA/cm2 can be drawn at an applied electric field of 2 V/μm. The field enhancement factor is 33025, while the turn-on field is only
1.4 V/μm. The emission current-time plot recorded at the pre-set value of emission current of 1 μA over a period of more than
3 h exhibits an initial increase and a subsequent stabilization of the emission current. The results reveal that the WO2.72 nanowire emitters synthesized by the solvothermal method are promising cathode materials for practical applications. 相似文献
25.
Fernandes RM VanBebber LH Bhattacharya S Chandra P Keppens V Mandrus D McGuire MA Sales BC Sefat AS Schmalian J 《Physical review letters》2010,105(15):157003
We demonstrate that the changes in the elastic properties of the FeAs systems, as seen in our resonant ultrasound spectroscopy data, can be naturally understood in terms of fluctuations of emerging nematic degrees of freedom. Both the softening of the lattice in the normal, tetragonal phase as well as its hardening in the superconducting phase are consistently described by our model. Our results confirm the view that structural order is induced by magnetic fluctuations. 相似文献
26.
Electron spin resonance studies have been carried out on Cu2+ ion doped in single crystals of cadmium maleate dihydrate at 303 and 77K. It has been found that Cu2+ enters this lattice interstitially. The spin Hamiltonian parameters have been evaluated and the ground state wave function
is found to be predominantly |X
2 −Y
2〉 with a slight admixture of |3Z
2 −r
2〉. 相似文献
27.
28.
Suresh Chandra 《Pramana》1980,14(1):41-46
The effect of dielectronic recombination as an excitation process in the intensity of solar x-ray lines of calcium ions is
investigated. It is found that x-ray line intensities are enhanced by 15% to 88% with the inclusion of dielectronic recombination
as an excitation mechanism. 相似文献
29.
C V A V B Chandra Raju 《Pramana》1985,24(4):L657-L661
Considering that the neutral interaction is free of triangle anomalies we derive an expression for the most general neutral
interaction with two neutral currents. We show that the Bargers version is a special case. We also determine the interaction
wheneverZ, D are mass eigen states and show that this differs from the Barger’s version in an essential way. 相似文献
30.
Theac anddc electroluminescence in CaS:Cu, Sm have been investigated. The luminescence spectra show three peaks in the visible region.
The brightness-voltage dependence satisfies the relationB=B
0 exp (−b/V
1/2) with two modes of variation. The nature of this dependence indc andac at different frequencies is discussed. The electroluminescence brightness also depends on the temperature of the phosphors
and shows a peak around 80.0;C. The electroluminescence efficiency increases with applied voltage up to 2200 V and this dependence
on V is explained on the basis of a transport process of the Schottky emission type. 相似文献