Ranjan Das

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Splitting of spectral lines is generally associated with corresponding splitting of appropriate energy levels. However, here we report our observation of the splittings of hyperfine lines in the time-resolved EPR spectrum of a stable free radical that participates in the quenching of an excited molecule. The observed splitting does not arise from any(More)
Quenching of excited states by a free radical is generally studied in systems where these two are separate entities freely moving in a liquid solution. Random diffusive encounters bring them together to cause the quenching and leave the spins of the radical polarized. In the dynamics of the radical-triplet pair mechanism of the generation of electron spin(More)
During the past two decades, several studies have established a significant role played by a thermally activated process in the electron spin relaxation of nitroxyl free radicals in liquid solutions. Its role has been used to explain the spin relaxation behavior of these radicals in a wide range of viscosities and microwave frequencies. However, no(More)
For the triplet mechanism (TM) of electron spin polarisation in photochemically generated free radicals to dominate, the chemical reaction has to be very fast and capable of competing with the electron spin-lattice relaxation process of the triplet. This is a well-established condition. Here we report a counter example of electron spin polarisation, where(More)
We report the results of our investigation on the electron spin relaxation mechanism of the monoanion of C60 fullerene in liquid solution. The solvent chosen was carbon disulfide, which is rather uncommon in EPR spectroscopy but proved very useful here because of its liquid state over a wide temperature range. The conditions for exclusive formation of the(More)
A series of molecules containing a naphthalene chromophore and a stable free radical 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) covalently linked by a spacer group of different lengths have been synthesized. In n-hexane solution, their photophysical behavior was studied and compared with a system of freely moving naphthalene and the free radical TEMPO.(More)
A field experiment was carried out during summer season in Assam Agricultural University, Jorhat, Assam to assess the physiological efficiency of seven blackgram genotypes under rainfed situation and to evaluate this response under foliar application of boron in respect to growth and yield. The treatments comprised of control (T1), foliar application of 100(More)
As the Fourier transform of time-series data is known as the spectrum, the Fourier transform of the logarithm of the time-series data is called the cepstrum of the data. When cepstral analysis is applied to free induction decay signals of free radicals showing first-order EPR spectra, the identification of nuclear hyperfine coupling constants becomes(More)
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