G P Gupta
Articles written in Pramana – Journal of Physics
Volume 61 Issue 6 December 2003 pp 1121-1128
Absolute measurement for He-α resonance (1s21S0−1s2p1
Volume 64 Issue 1 January 2005 pp 141-146
The effect of dielectronic recombination in determining charge-state distribution and radiative emission from a laser-produced carbon plasma has been investigated in the collisional radiative ionization equilibrium. It is observed that the relative abundances of different ions in the plasma, and soft X-ray emission intensity get significantly altered when dielectronic recombination is included. Theoretical estimates of the relative population of CVI to CV ions and ratio of line intensity emitted from them for two representative formulations of dielectronic recombination are presented.
Volume 74 Issue 6 June 2010 pp 983-993 Research Articles
Plasma produced by a 355 nm pulsed Nd:YAG laser with a pulse duration of 6 ns focussed onto a copper solid sample in air at atmospheric pressure is studied spectroscopically. The temperature and electron density characterizing the plasma are measured by time-resolved spectroscopy of neutral atom and ion line emissions in the time window of 300–2000 ns. An echelle spectrograph coupled with a gated intensified charge coupled detector is used to record the plasma emissions. The temperature is obtained using the Boltzmann plot method and the electron density is determined using the Saha– Boltzmann equation method. Both parameters are studied as a function of delay time with respect to the onset of the laser pulse. The results are discussed. The time window where the plasma is optically thin and is also in local thermodynamic equilibrium (LTE), necessary for the laser-induced breakdown spectroscopy (LIBS) analysis of samples, is deduced from the temporal evolution of the intensity ratio of two Cu I lines. It is found to be 700–1000 ns.
Volume 75 Issue 6 December 2010 pp 1135-1139 Conributed Papers
Spectrally resolved laser-induced fluorescence technique was used to uniquely assign total angular momentum (𝐽) values to high-lying even-parity energy levels of atomic samarium. Unique 𝐽 value assignment was done for seven energy levels in the energy region 34,800–36,200 cm-1 , recently observed and reported in the literature.
Volume 75 Issue 6 December 2010 pp 1145-1150 Conributed Papers
It is a well-known fact that laser-induced breakdown spectroscopy (LIBS) has emerged as one of the best analytical techniques for multi-elemental compositional analysis of samples. We report assembling and optimization of LIBS set up using high resolution and broad-range echelle spectrograph coupled to an intensified charge coupled device (ICCD) to detect and quantify trace elements in environmental and clinical samples. Effects of variations of experimental parameters on spectroscopy signals of copper and brass are reported. Preliminary results of some plasma diagnostic calculations using recorded time-resolved optical emission signals are also reported for brass samples.
Volume 82 Issue 2 February 2014 pp 403-408 Contributed Papers
In this paper, we report the investigations of lifetime measurement of odd-parity energy level 19009.52 cm-1 of Sm I using simultaneous detection of laser-induced fluorescence and laserinduced photoionization signals employing pump–probe technique. To the best of our knowledge, this is for the first time that the results obtained using laser-induced fluorescence and photoionization techniques have been compared with each other. The obtained results match well with those reported in the literature.
Volume 93 | Issue 5
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