Line broadening studies in low energy plasma focus

Optical emission spectroscopic studies were carried out to characterise the plasma leading to the estimation of two plasma parameters, electron density and temperature. These experiments were conducted on a 2 kJ plasma device which is equipped with squirrel cage electrode configuration enclosed in a glass vacuum chamber filled with hydrogen at a pressure of 5 mbar. Spectral emissions obtained from each flash were photographed in the region of 4000–6000 Å using one metre Czerny-Turner spectrograph cum monochromator. Detailed examination of the observed features showed that theH _β andH _λ lines of hydrogen showed significant broadening of the order of 35 Å FWHM which is due to Stark effect expected in high density plasmas. Further several atomic lines of Cu and Zn from the electrode material (brass) showed broadening which was due to quadratic Stark effect. A comparative study of the broadening of lines obtained in DC arc, hollow cathode and plasma focus was made. Electron density from Stark broadened hydrogen lines and quadratic Stark Coefficient C₄ for the CuI and ZnI lines were evaluated. The excitation temperature was determined from the line intensity ratio method using CuI lines.     

Focussing properties of a holographic plane diffraction grating

A plane holographic diffraction grating is the simplest grating, yet very important component for many optical devices. Very little has been done with regards to its focusing properties and stigmatic conditions. In this paper, we discuss a holographic plane diffraction grating and show that the grating can exhibit focusing properties under some conditions. We also discuss the conditions for zero astigmatism.     

Finite-range DWBA analyses of (dt) and (d3He) reactions on 64Zn at Ed = 13 MeV

Exact finite-range DWBA analyses of ($\text{d}\text{, t}\text{)}$ and $\text{(}\text{d}\text{d}$, ³He) reactions have been performed for an ⁶⁴Zr target at an incident deuteron energy of 13.0 MeV, leading to the ground states of the residual nuclei. The microscopic overlap functions for (d, t) and (d, ³He) systems obtained by using the Phillips triton wavefunctions have been used as projectile form factors into the calculation. The results are compared with zero-range DWBA calculations taking the finite-range effects into account by means of a local energy approximation. The results obtained by finite-range and zero-range calculations for differential cross sections as well as vector and tensor analysing powers are compared with the experimental data. The range of validity of the local energy approximation is discussed.     

Vibrational dynamics of polyurydilic acid

A study of the normal modes of vibration and their dispersion in polyurydilic acid (polyU) is reported using Wilson's GF Matrix method as modified by Higgs. This is done for the `bare' as well as for the helix `loaded' with uracil. Confusion that has prevailed regarding the assignments of the observed modes at 810 and 572 cm⁻¹ is cleared and it is shown that the so called bare helix (polyU-U) has a different minimum energy state and hence spectrally different. Dispersion of the normal modes in the two helices shows marked differences which are characteristic of the extent of electrical/mechanical coupling along the chain and between the chain and the base. Values predicted for the heat capacity as a function of temperature for polyU is also reported.     

Mass spectral fragmentation pattern of 2,3-dimethyl- and 2-methyl-3-phenyl-4-arylazoisoxazol-5-ones

2,3-Dimethyl-4-arylazoisoxazol-5-ones and 2-methyl-3-phenyl-4-aryiazoisoxazol-5-ones undergo considerable fragmentation on electron impact. The base peaks in the mass spectra are at mass 56 and 118 respectively attributed to the N-methylacetonitrile cation and the N-methylbenzonitrile cation.     

A reinvestigation of the cyclodesulfurization of thiosemicarbazides

A recent report describing the preparation of 2-(substituted-amino)-3,4-dihydro-5H-1,3,4-benzotriazepin-5-ones (3), by the cyclodesulfurization of hydrazides prepared from o-aminobenzoylhydrazine ( 1 ) and isothiocyanates, is erroneus. The products resulting from this reaction sequence are, instead, 2-(substituted-amino)-5-(o-aminophenyl)-1,3,4-oxadiazoles ( 4 ). Alternate syntheses of the oxadiazoles led to the correct structural assignments.     

A new conformer of 20-hydroxyecdysone from Sesuvium portulacastrum: an x-ray crystallographic study

X-ray single crystal analysis of 20-hydroxyecdysone (20E, 2), an important insect moulting hormone, isolated from Sesuvium portulacastrum Linn. was found to exhibit a unique stereochemical configuration revealing it to be a different conformer (polymorph) possessing the aliphatic chain atoms in a trans configuration. Moreover, the analysis also revealed the presence of three molecules of water of crystallisation thereby restricting the freedom of the aliphatic side chain.     

Synthesis of 1,4-dihydro-4-methyl-1-phenyl-5H-1,3,4-benzotriazepin-5-ones

The synthesis of 1,4-dihydro-4-methyl-1-phenyl-5H-1,3,4-benzotriazepin-5-one ( 4a ) and its 8-chloro analog ( 4b ) is described. Attempted synthesis of the 2-methyl analog of 4a from 2-(phenylamino)benzoic acid 1-methylhydrazide ( 10 ) and triethyl orthoaeetate led only to the Schiff base intermediate, 2-(phenylamino)benzoic acid 2-(1-ethoxyethylidene)-1-methylhydrazide ( 11 ). Cyclization of 11 was attempted unsuccessfully with a variety of reagents. The intere?ting reaction products from the treatment of 11 with trifluoroacetic acid are described.     

Green Synthesis and Biological Evaluation of Novel Fused 6-(2-Chloro-4-fluorophenyl)-9-arylimidazo[1,2-a][1,8]naphthyridine Derivatives Catalyzed by DABCO

Russian Journal of General Chemistry - An efficient synthesis of 6-(2-chloro-4-fluorophenyl)-9-phenylimidazo[1,2-a][1,8]naphthyridine derivatives by the reaction of phenacyl bromide with...