Individual color centers in diamond have recently emerged as a promising solid-state platform for... more Individual color centers in diamond have recently emerged as a promising solid-state platform for quantum communication and quantum information processing systems, as well as sensitive nanoscale magnetometry with optical read-out. Performance of these systems can be significantly improved by engineering optical properties of color centers using nanophotonic approaches. In this work we describe a highflux, room temperature, source of single photons based on an individual Nitrogen-Vacancy (NV) center embedded in a ...
We have studied the optical gain of Fullerene C60 and Fullerene C70 in toluene solution by variab... more We have studied the optical gain of Fullerene C60 and Fullerene C70 in toluene solution by variable strip method. The technique involves the comparison of fluorescence emission at different length of pumped material. The gain is found to be positive for a very narrow range of concentration. The optical gain is maximum at 40 μM concentration for both fullerene molecules. Optical gain is highly concentration dependent and milli molar concentration is not the optimum concentration for the measurement of optical gain. But the value of peak gain for fullerene C70 is more than that of fullerene C60. It may be due to the extent of twisted intermolecular charge transfer (TICT) formation in the excited state is larger for fullerene C70. Therefore, optical gain for fullerene C60 is less than fullerene C70. This is thus an important distinguishing parameter of two sister molecules.
Spectrochimica Acta Part A-molecular and Biomolecular Spectroscopy, 2005
The geometries of hydroxy derivatives of 1,4-naphthoquinone (NQ), viz., 2-hydroxy-1,4-naphthoquin... more The geometries of hydroxy derivatives of 1,4-naphthoquinone (NQ), viz., 2-hydroxy-1,4-naphthoquinone (2HNQ), 5-hydroxy-1,4-naphthoquinone (5HNQ), and 5,8-dihydroxy-1,4-naphthoquinone (DHNQ), have been optimized using the semiempirical and ab initio theoretical methods. Semiempirical methods used for the optimization are Austin Model 1 (AM1) and Zerner's Intermediate Neglect of Differential Overlap/1(ZINDO/1). For ab initio calculations the 6-31G* basis set is used. The electronic spectra of 1,4-naphthoquinone and its hydroxy derivatives are calculated using the semiempirical Zerner's Intermediate Neglect of Differential Overlap/Spectroscopy (ZINDO/S) method employing the geometries optimized at AM1, ZINDO/1 and ab initio levels and compared with their electronic absorption spectra measured by us. For hydroxy substituted systems, such calculations for spectral assignments are made for the first time. It is found that though the predictions of the three theoretical methods for the geometries are similar, the predictions of the ZINDO/S method using the ZINDO/1 optimized geometries, are better for the transition wavelengths in the visible region of the hydroxy substituted naphthoquinones, especially for 5HNQ and DHNQ.
Abstract Cadmium sulphide nanoparticles were synthe-sized by chemical displacement reaction metho... more Abstract Cadmium sulphide nanoparticles were synthe-sized by chemical displacement reaction method using cadmium nitrate as cadmium source and ammonium sul-phide as sulphur source. The CdS samples are character-ized using X-ray diffraction, UVVis ...
Cadmium sulphide nanoparticles were synthesized by chemical displacement reaction method using ca... more Cadmium sulphide nanoparticles were synthesized by chemical displacement reaction method using cadmium nitrate as cadmium source and ammonium sulphide as sulphur source. The CdS samples are characterized using X-ray diffraction, UV–Vis spectroscopy, FTIR spectroscopy, scanning electron microscopy and impedance spectroscopy. CdS nanoparticles are found to possess cubic structure with the crystallite size ~10 nm. The absorption spectra of synthesized CdS nanoparticles revealed the blue shift in excitonic transitions with respect to CdS bulk material, clearly confirming the formation of nanoparticles. The dielectric properties of CdS nanoparticles are studied in the frequency range 103–107 Hz at room temperature. The dielectric properties of CdS nanoparticles are found to be significantly enhanced specially in the low frequency range due to confinement.
Abstract. We have studied the optical gain of Fullerene C60 and Fullerene C70 in toluene solution... more Abstract. We have studied the optical gain of Fullerene C60 and Fullerene C70 in toluene solution by variable strip method. The technique involves the comparison of fluorescence emission at different length of pumped material. The gain is found to be positive for a very ...
Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy, 2013
The fluorescence decay time of Fullerenes C60 and C70 in pure form as well as in mixture with Cou... more The fluorescence decay time of Fullerenes C60 and C70 in pure form as well as in mixture with Coumarin C440 and Quinizarine dyes are studied. Results indicate that the decay of pure fullerenes is constant throughout the solute concentration and it is also independent of excitation wavelength, whereas in the case of mixture with dyes different behavior is noticed. We have also calculated the Stern-Volmer quenching constant and optical gain of both the fullerenes from which it is found that the optical gain is positive for Fullerene C70 only in a very narrow range of concentration.
Individual color centers in diamond have recently emerged as a promising solid-state platform for... more Individual color centers in diamond have recently emerged as a promising solid-state platform for quantum communication and quantum information processing systems, as well as sensitive nanoscale magnetometry with optical read-out. Performance of these systems can be significantly improved by engineering optical properties of color centers using nanophotonic approaches. In this work we describe a highflux, room temperature, source of single photons based on an individual Nitrogen-Vacancy (NV) center embedded in a ...
We have studied the optical gain of Fullerene C60 and Fullerene C70 in toluene solution by variab... more We have studied the optical gain of Fullerene C60 and Fullerene C70 in toluene solution by variable strip method. The technique involves the comparison of fluorescence emission at different length of pumped material. The gain is found to be positive for a very narrow range of concentration. The optical gain is maximum at 40 μM concentration for both fullerene molecules. Optical gain is highly concentration dependent and milli molar concentration is not the optimum concentration for the measurement of optical gain. But the value of peak gain for fullerene C70 is more than that of fullerene C60. It may be due to the extent of twisted intermolecular charge transfer (TICT) formation in the excited state is larger for fullerene C70. Therefore, optical gain for fullerene C60 is less than fullerene C70. This is thus an important distinguishing parameter of two sister molecules.
Spectrochimica Acta Part A-molecular and Biomolecular Spectroscopy, 2005
The geometries of hydroxy derivatives of 1,4-naphthoquinone (NQ), viz., 2-hydroxy-1,4-naphthoquin... more The geometries of hydroxy derivatives of 1,4-naphthoquinone (NQ), viz., 2-hydroxy-1,4-naphthoquinone (2HNQ), 5-hydroxy-1,4-naphthoquinone (5HNQ), and 5,8-dihydroxy-1,4-naphthoquinone (DHNQ), have been optimized using the semiempirical and ab initio theoretical methods. Semiempirical methods used for the optimization are Austin Model 1 (AM1) and Zerner's Intermediate Neglect of Differential Overlap/1(ZINDO/1). For ab initio calculations the 6-31G* basis set is used. The electronic spectra of 1,4-naphthoquinone and its hydroxy derivatives are calculated using the semiempirical Zerner's Intermediate Neglect of Differential Overlap/Spectroscopy (ZINDO/S) method employing the geometries optimized at AM1, ZINDO/1 and ab initio levels and compared with their electronic absorption spectra measured by us. For hydroxy substituted systems, such calculations for spectral assignments are made for the first time. It is found that though the predictions of the three theoretical methods for the geometries are similar, the predictions of the ZINDO/S method using the ZINDO/1 optimized geometries, are better for the transition wavelengths in the visible region of the hydroxy substituted naphthoquinones, especially for 5HNQ and DHNQ.
Abstract Cadmium sulphide nanoparticles were synthe-sized by chemical displacement reaction metho... more Abstract Cadmium sulphide nanoparticles were synthe-sized by chemical displacement reaction method using cadmium nitrate as cadmium source and ammonium sul-phide as sulphur source. The CdS samples are character-ized using X-ray diffraction, UVVis ...
Cadmium sulphide nanoparticles were synthesized by chemical displacement reaction method using ca... more Cadmium sulphide nanoparticles were synthesized by chemical displacement reaction method using cadmium nitrate as cadmium source and ammonium sulphide as sulphur source. The CdS samples are characterized using X-ray diffraction, UV–Vis spectroscopy, FTIR spectroscopy, scanning electron microscopy and impedance spectroscopy. CdS nanoparticles are found to possess cubic structure with the crystallite size ~10 nm. The absorption spectra of synthesized CdS nanoparticles revealed the blue shift in excitonic transitions with respect to CdS bulk material, clearly confirming the formation of nanoparticles. The dielectric properties of CdS nanoparticles are studied in the frequency range 103–107 Hz at room temperature. The dielectric properties of CdS nanoparticles are found to be significantly enhanced specially in the low frequency range due to confinement.
Abstract. We have studied the optical gain of Fullerene C60 and Fullerene C70 in toluene solution... more Abstract. We have studied the optical gain of Fullerene C60 and Fullerene C70 in toluene solution by variable strip method. The technique involves the comparison of fluorescence emission at different length of pumped material. The gain is found to be positive for a very ...
Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy, 2013
The fluorescence decay time of Fullerenes C60 and C70 in pure form as well as in mixture with Cou... more The fluorescence decay time of Fullerenes C60 and C70 in pure form as well as in mixture with Coumarin C440 and Quinizarine dyes are studied. Results indicate that the decay of pure fullerenes is constant throughout the solute concentration and it is also independent of excitation wavelength, whereas in the case of mixture with dyes different behavior is noticed. We have also calculated the Stern-Volmer quenching constant and optical gain of both the fullerenes from which it is found that the optical gain is positive for Fullerene C70 only in a very narrow range of concentration.
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