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81.
The process of infrared multiple photon dissociation (IRMPD) of molecules is of great fundamental importance and has practical
significance, such as isotope separation etc. Unfortunately, a clear insight into the process has been hindered by the bewildering
array of important variables affecting MPD. The dissociation probability γ (φ) i.e. the yield has been found to be a sensitive
function of laser fluence φ along with numerous other parameters like laser frequency, gas pressure etc. We have shown that
in single frequency IRMPD, an accurate quantitative characterization of the dissociation probability can be adequately expressed
by a ‘power law’ model with two fitting parameters namely critical fluence, φc and multiphoton order,m. This model was exploited in analysing our MPD results on various systems. However, the small isotope shift encountered in
heavy elements and the sticking phenomenon observed in small light molecules restrict respectively the separation factor and
the dissociation yield. These problems can effectively be tackled by irradiation with multifrequency laser beams which can
be chosen appropriately on the basis of spectroscopic features. Based on our success in single frequency model, multifrequency
IRMPD is modelled by a functional form containing the product of power law terms for individual fluences on irradiation frequencies.
This model is successfully benchmarked with our experimental results on multifrequency LIS of tritium. Such knowledge can
be utilized for appropriate separation process design, evaluation and optimization. 相似文献
82.
Background
Organic light emitting devices (OLED) are becoming important and characterisation of them, in terms of structure, charge distribution, and intermolecular interactions, is important. Tris(8-hydroxyquinolinato)-aluminium(III), known as Alq3, an organomettalic complex has become a reference material of great importance in OLED. It is important to elucidate the structural details of Alq3 in its various isomeric and solvated forms. Solid-state nuclear magnetic resonance (NMR) is a useful tool for this which can also complement the information obtained with X-ray diffraction studies. 相似文献83.
Bhoyar R. A. Nayak A. C. Wankhede S. P. Belsare P. D. Moharil S. V. 《Physics of the Solid State》2021,63(6):948-952
Physics of the Solid State - New results on luminescence in Ba2ScCl7 are reported. Lanthanides Eu2+ and Ce3+ were chosen as activators. The phosphors could be prepared by a simple wet chemical... 相似文献
84.
A modular approach to 5-acylated naphtho[2,1-b]benzofurans was developed where Sonogashira cross-coupling and intramolecular alkyne carbonyl metathesis were sequentially employed to build the aromatic benzene C ring of naphtho[2,1-b]benzofuran with an acyl group at the C5 position. 相似文献
85.
S. N. V. M. S. Gupta A. K. Nayak U. B. Misra Balaji Rao Yarasi C. Phani Babu G. Kalyanakrishnan 《Journal of Radioanalytical and Nuclear Chemistry》2017,313(3):571-579
The present paper describes a new analytical method developed for direct determination of boron in steels using radio frequency glow discharge optical emission spectrometer. “Single parameter alternative method” technique has been used to optimize the various experimental conditions of glow discharge plasma such as forward power, gas pressure inside plasma chamber, pre-integration time, and integration time. Different emission lines for boron were studied and inter element interference effect is also discussed in the paper. A complete statistical analysis has been done to validate the developed method. A RSD of less than ±5% is achieved for boron in the range of 0.0010–0.020% in Steels using this method. 相似文献
86.
Yughandhar Sreedhar Neelam Rekha Dasari P. Reddy Prasad M. Sankar Nayak 《Journal of Saudi Chemical Society》2010,14(2):149-155
A novel analytical reagent 4-(2-hydroxy phenyl ethaminodiol), benzene-1,3-diol(4-2-HPEDB-1,3,D) was synthesized for the determination of molybdenum(VI). The present paper reveals the detailed study of electroanalytical behaviour for [Mo-(4-2-HPEDB-1,3,D)] complex under optimized conditions. The peak obtained for [Mo-(4-2-HPEDB-1,3,D)] prevent the interference of foreign ions which shows the sensitivity of the proposed method. The linearity was maintained at the concentration range of 0.5–200 μg/mL at pH 4.5 with correlation factor 0.9997. The present method was successfully applied for the analysis of molybdenum(VI) in biological fluids and plant material. The results obtained from the proposed method show good agreement with reference method. 相似文献
87.
88.
Vikas Jain A.K. Nayak P.K. Vijayan D. Saha R.K. Sinha 《Experimental Thermal and Fluid Science》2010,34(6):776-787
Natural circulation as a mode of heat removal is being considered as a prominent passive feature in the innovative nuclear reactor designs, particularly in boiling-water-reactors, due to its simplicity and economy. However, boiling natural circulation system poses many challenges to designer due to occurrence of various kinds of instabilities such as excursive instability, density wave oscillations, flow pattern transition instability, geysering and metastable states in parallel channels. This problem assumes greater significance particularly at low-pressures i.e. during startup, where there is great difference in the properties of two phases. In light of this, a parallel channel loop has been designed and installed that has a geometrical resemblance to the pressure-tube-type boiling-water-reactor, to investigate into the behavior of boiling natural circulation. The loop comprises of four identical parallel channels connected between two common plenums i.e. steam drum and header. The recirculation path is provided by a single downcomer connected between steam drum and header. Experiments have been conducted over a wide range of power and pressures (1–10 bar). Two distinct unstable zones are observed with respect to power i.e. corresponding to low power (Type-I) and high power (Type-II) with a stable zone at intermediate powers. The nature of oscillations in terms of their amplitude and frequency and their evolution for Type-I and Type-II instabilities are studied with respect to the effect of heater power and pressure. This paper discusses the evolution of unstable and stable behavior along with the nature of flow oscillation in the channels and the effect of pressure on it. 相似文献
89.
Finite clusters of atoms or molecules, typically composed of about 50 particles (and often as few as 13 or even less) have
proved to be useful prototypes of systems undergoing phase transitions. Analogues of the solid-liquid melting transition,
surface melting, structural phase transitions and the glass transition have been observed in cluster systems. The methods
of nonlinear dynamics can be applied to systems of this size, and these have helped elucidate the nature of the microscopic
dynamics, which, as a function of internal energy (or ‘temperature’) can be in a solidlike, liquidlike, or even gaseous state.
The Lyapunov exponents show a characteristic behaviour as a function of energy, and provide a reliable signature of the solid-liquid
melting phase transition. The behaviour of such indices at other phase transitions has only partially been explored. These
and related applications are reviewed in the present article. 相似文献
90.
Chetan Nayak 《General Relativity and Gravitation》1991,23(9):981-989
Einstein-Maxwell theory in 2+1 dimensions is considered as a toy model for the 3+1 theory and as a means for understanding field theories without a background space-time geometry. Two possible approaches to the quantization of this theory are presented, one based on a Schwinger-Tomonaga time evolution equation and the other on a loop space construction, and the problems arising in both of these are discussed. 相似文献