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41.
Sandeep Kumar Maurya Dheerendra Yadav Debabrata Goswami 《Journal of fluorescence》2016,26(5):1573-1577
We investigate the effect of cetyl-trimethyl-ammonium-bromides (CTAB) concentration on the fluorescence of Rhodamine-6G in water. This spectroscopic study of Rhodamine-6G in presence of CTAB was performed using two-photon-induced-fluorescence at 780 nm wavelength using high repetition rate femtosecond laser pulses. We report an increment of ~10 % in the fluorescence in accordance with ~12 % enhancement in the absorption intensity of the dye molecule around the critical micellar concentration. We discuss the possible mechanism for the enhancement in the two-photon fluorescence intensity and the importance of critical micellar concentration. 相似文献
42.
Goswami D 《Physical review letters》2002,88(17):177901
Selective control of decoherence is demonstrated for a multilevel system by generalizing the instantaneous phase of any chirped pulse as individual terms of a Taylor series expansion. In the case of a simple two-level system, all odd terms in the series lead to population inversion, while the even terms lead to self-induced transparency. These results also hold for multiphoton transitions that do not have any lower-order photon resonance or any intermediate virtual state dynamics within the laser pulse width. Such results form the basis of a robustly implementable CNOT gate. 相似文献
43.
The ψ′ → ψπ0 decay rate is studied in a chiral symmetry breaking scheme by including effects from π0-η mixing only. The result obtained is in very good agreement with the experiment. 相似文献
44.
Vibrational dephasing of the nitrogen molecule is known to show highly interesting anomalies near its gas-liquid critical point. Here we present theoretical and computational studies of the Raman linewidth of nitrogen along the critical isochore. The linewidth is found to have a lambda-shaped temperature dependence near the critical point. As observed in experimental studies, the calculated line shape becomes Gaussian as the critical temperature (T(c)) is approached. Both the present simulation and a mode coupling theory analysis show that the slow decay of the enhanced density fluctuations near the critical point, probed at the subpicosecond time scales by vibrational frequency modulation, along with an enhanced vibration-rotation coupling, are the main causes of the observed anomalies. 相似文献
45.
Gautam Rajesh Kumar Seth Debabrata 《Journal of Thermal Analysis and Calorimetry》2020,140(6):2633-2640
Journal of Thermal Analysis and Calorimetry - We have reported the thermal conductivities of three deep eutectic solvents (DESs). We have used choline chloride, N,N-diethyl ethanol ammonium... 相似文献
46.
Summary In aqueous solution [Cu(bigH)2]2+ (bigH=biguanide) reacts with 2,2-bipyridyl (bipy) and 1,10-phenanthroline (phen) through intermediate formation of ternary complexes [Cu(bigH)(L)]2+ and [Cu(bipy)(phen)]2+ and binary complexes [CuL2]2+ (L=bipy, phen). The rates of the different steps have been followed in borax buffer (pH 8.0±0.1) by stopped-flow spectrophotometry. For each step kobs=k0+kL[L] and the kL path appears to be associative. H and S values for the kL path conform to an isokinetic trend. 相似文献
47.
Dynamics of water molecules in the grooves of DNA are of great interest both for practical (functionality of DNA) and fundamental (as examples of confined systems) interest. Here the authors employ atomistic molecular dynamics simulations to understand varying water dynamics at the minor and the major grooves of a 38 base-pair long DNA duplex in water. In order to understand and quantify the diversity in the nature of hydrogen bond due to many hydrogen bond donors and acceptors present in the four bases, they have undertaken study of hydrogen bond lifetime (HBLT) correlation functions of all the specific hydrogen bonds between the base atoms and water molecules. They find that the HBLT correlation functions are in general multiexponential, with the average lifetime depending significantly on the specificity and may thus be biologically relevant. The average hydrogen bond lifetime is longer in the minor groove than that in the major groove by almost a factor of 2. Analysis further shows that water hydrogen bonds with phosphate oxygen have substantially shorter lifetimes than those with the groove atoms. They also compute two different orientational time correlation functions (OTCFs) of the water molecules present at the major and the minor grooves and attempt to correlate OTCF with HBLT correlation function. The OTCFs in the minor groove exhibit three time scales, with the time constant of the slowest component one to two orders of magnitude longer than what is observed for bulk water. A slow component is also present for the major groove water but with shorter time constant. Interestingly, correlation between reformations allowed HBLT correlation function [C(HB)(t)] and the OTCF markedly deviates from each other in the grooves, indicating enhanced rigidity of water molecules in the grooves. 相似文献
48.
We demonstrate coded self-assembly in nanostructures using the code seeded at the component level through computer simulations.
Defects or cavities occur in all natural assembly processes including crystallization and our simulations capture this essential
aspect under surface minimization constraints for self-assembly. Our bottom-up approach to nanostructures would provide a
new dimension towards nanofabrication and better understanding of defects and crystallization process.
相似文献
49.
We introduce a single step memory dependence in the fully chaotic logistic map. This makes it a two dimensional system in general. However, we show that by using composite functions to define two one dimensional maps, it is possible to obtain some analytic results for the bifurcation structure. Numerical results support the calculated bifurcation scheme and, in addition, yield a further insight which allows the calculation of the convergence ratio for a new period adding scenario. 相似文献
50.
Shyamaprosad Goswami Debabrata Sen Nirmal Kumar Das Giridhari Hazra 《Tetrahedron letters》2010,51(42):5563-5566
A 1,8-naphthalimide-based colorimetric fluorescence perinone dye, receptor 1 is reported herein for the selective detection of Cu2+ over the other heavy and transition metal ions. Receptor 1 shows a strong colorimetric change from orange to purple and a dramatic enhancement of fluorescence intensity due to cation-induced excited state internal charge transfer during the sensing event, that is, a dual optical response that would facilitate naked-eye detection of Cu2+. 相似文献