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[en] Coal is used for one third of the whole energy production all over the world and makes up to 40% of the electricity generation. It also plays a dominant role in industries such as iron and steel. Nearly 80% of the total electricity generated in India is from coal. But from the recent few years the production and consumption of coal is reduced worldwide. This shift largely reflects structural factors: the growing accessibility and competitiveness of natural gas and renewable energy resources, united with the government and societal pressure to shift towards clean, green and low carbon generating fuels. No doubt coal is very important fuel for human being but after combustion process coal leaves a large amount of coal residue and its utilization is an important area of study. The residue contains a wide range of elements including many toxic elements. For suitable use of coal residues elemental characterization is needed. Particle induced gamma ray emission (PIGE) is a nondestructive nuclear analytical technique which is suitable for detection and measurement of concentration of low Z elements. In PIGE, the target nuclei present in the sample are irradiated with suitable energetic charged particles to excite. These nuclei are excited through (p,p'γ), (p,nγ) or (p,αγ) reactions. The emitted gamma rays after de-excitation of nuclei are detected and counted for identification of the elements and their concentration in the sample.
[en] Total cross sections for quenching of metastable hydrogen and deuterium atoms in collisions with some selected molecules have been measured. The velocity range of the metastable projectiles is from 0.48 to 3.6x106cm/sec. The cross sections have been compared with the predictions of two theoretical treatments by Gersten and Semini which both assume collisional quenching to be due to the interaction of the metastable atom with the molecule's lowest order electric multipole moment
[en] Photophysical properties of BODIPY dyes containing acetyl acetone and benzoyl acetone BF2 unit as an electron accepting substituent at beta position linked via double bond have been investigated using a wide range of solvents of different polarities. The substitution effect at beta position of the BODIPY dyes on their absorption, emission and quantum yield of fluorescence have been the aim of present study. For the synthesized BODIPY dyes fluorescence quantum yields and lifetimes show very sharp decrease with an increase in the solvent polarity, suggesting the involvement of highly polar ICT state de-excitation mechanism along with the local excitation process. The polarity dependent changes in average fluorescence life time and quantum yield values rationalize the formation of ICT states.