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21.
T. Mathavan M. Kumara Dhas C. V. Kanimozhi M. A. Jothi Rajan S. Umapathy A. Ramasubbu 《光谱学快报》2014,47(8):642-648
Electron paramagnetic resonance, Fourier transform infrared, and ultraviolet-visible studies were carried out for pure and histidine-functionalized multiwalled carbon nanotubes. Electron paramagnetic resonance absorption spectral data were found to be the best fit for the Gaussian lineshape. The g-values indicate the presence of magnetic impurities in the samples and the interaction between the localized electrons and delocalized electrons in the nanotubes trapped at defects or magnetic ion sites. The electron spin concentration decreases with increasing concentration of histidine, which implies that the unpaired electrons undergo a reduction process in the histidine-functionalized multiwalled carbon nanotubes. Fourier transform infrared study confirms the presence of functional groups in pure and histidine-functionalized multiwalled carbon nanotubes. Ultraviolet-visible study reveals the formation of a charge transfer complex in histidine-functionalized multiwalled carbon nanotubes. 相似文献
22.
S. Natarajan G. P. Chitra S. A. Martin Britto Dhas S. Athimoolam 《Crystal Research and Technology》2008,43(7):713-719
A new semiorganic crystal, L‐glutamic acid hydrobromide, C5H10NO4Br (GHB) has been grown from aqueous solution. The single crystal X‐ray analysis of the crystal showed that it belongs to the non‐centrosymmetric P212121 space group with protonated glutamic acid as cation and bromine as anion. The back‐bone conformations of the amino acid are in cis and trans form. The side‐chain conformations are observed to be in gauche I / trans / cis / trans forms. The characteristic ‘head‐to‐tail’ hydrogen bonding interaction is observed through a chain C(5) motif. Further, the crystal structure is stabilized by an intricate three‐dimensional hydrogen bonding network. TGA/DTA showed that the grown crystals are thermally stable upto 219 °C without any phase transition. The functional groups responsible for the various modes of vibrations were identified by using FTIR spectroscopy. UV‐Vis‐NIR spectra showed that the crystals have excellent transparency in the visible and infrared regions. The second harmonic generation (SHG) conversion efficiency was investigated to explore the NLO characteristics of the material. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
23.
The reaction of peroxomonophosphoric acid and hydrazinium ion in acid perchlorate solutions occurs as per stoichiometry (i), and the rate law (ii) at large [N2H5 +], where K′d is the first acid dissociation constant of H3PO5 and k 1 and k 2 are rate constants found to be 2.6 × 10?4 s?1 and 5.0 × 10?2 M?1 s?1, respectively, at 35°. The reaction is greatly catalyzed by iodide ions. The mechanism involves a redox cycle I?/I2 and the rate is independent of [N2H5 +] in the presence of iodide ions. K′d was found to be 0.55 M?1 and independent of temperature. 相似文献
24.
S.A. Martin Britto Dhas 《Optics Communications》2007,278(2):434-438
Single crystals of glycine nitrate [(C2H6NO2)+ · (NO3)−] were grown using submerged seed solution method. The crystals were characterized by using single crystal X-ray diffraction and density measurements. Spectroscopic, thermal and optical studies were carried out for analyzing the presence of the functional groups, thermal stability, decomposition and transparency of the sample. These studies showed that the crystals are thermally stable upto 145 °C and transparent for the fundamental and second harmonic generation of Nd:YAG (λ = 1064 nm) laser. Second harmonic generation (SHG) conversion efficiency was investigated to explore the NLO characteristics of this material. Microhardness and dielectric studies were also carried out. 相似文献