The Experts below are selected from a list of 234 Experts worldwide ranked by ideXlab platform
Nadia Singh - One of the best experts on this subject based on the ideXlab platform.
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14n NQR Spectrum of sildenafil citrate
Hyperfine Interactions, 2015Co-Authors: David Stephenson, Nadia SinghAbstract:The 14N nuclear quadrupole resonance (NQR) Spectrum of sildenafil citrate tablets has been recorded allowing the quadrupole coupling constants and asymmetry parameters of all six unique nitrogen atoms in its structure to be determined. A density function calculation gives results that are largely in agreement with the experimental values.
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^14 N NQR Spectrum of sildenafil citrate
Hyperfine Interactions, 2015Co-Authors: David Stephenson, Nadia SinghAbstract:The ^14N nuclear quadrupole resonance (NQR) Spectrum of sildenafil citrate tablets has been recorded allowing the quadrupole coupling constants and asymmetry parameters of all six unique nitrogen atoms in its structure to be determined. A density function calculation gives results that are largely in agreement with the experimental values.
David Stephenson - One of the best experts on this subject based on the ideXlab platform.
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14n NQR Spectrum of sildenafil citrate
Hyperfine Interactions, 2015Co-Authors: David Stephenson, Nadia SinghAbstract:The 14N nuclear quadrupole resonance (NQR) Spectrum of sildenafil citrate tablets has been recorded allowing the quadrupole coupling constants and asymmetry parameters of all six unique nitrogen atoms in its structure to be determined. A density function calculation gives results that are largely in agreement with the experimental values.
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^14 N NQR Spectrum of sildenafil citrate
Hyperfine Interactions, 2015Co-Authors: David Stephenson, Nadia SinghAbstract:The ^14N nuclear quadrupole resonance (NQR) Spectrum of sildenafil citrate tablets has been recorded allowing the quadrupole coupling constants and asymmetry parameters of all six unique nitrogen atoms in its structure to be determined. A density function calculation gives results that are largely in agreement with the experimental values.
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^14N NQR and relaxation in ammonium nitrate
Hyperfine Interactions, 2015Co-Authors: David StephensonAbstract:The complete ^14N nuclear quadrupole resonance (NQR) Spectrum of ammonium nitrate is presented recorded using two double resonance techniques – double contact cross relaxation and zero field NQR. The spectra gave the quadrupole coupling constant (Qcc) and asymmetry parameter ( η ) values for the nitro of 611 kHz, 0.229 and that for the ammonium nitrogen of 242 kHz, 0.835. The three relaxation transition probabilities have been determined for both the nitro and ammonium nitrogen atoms. The bi-exponential relaxation times (T _1) were measured at 295 K. The values for nitro are 16.9 s and 10.5 s and that of the ammonium are 23.0 s and 16.4 s.
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14 N NQR and relaxation in ammonium nitrate
Hyperfine Interactions, 2015Co-Authors: David StephensonAbstract:The complete 14N nuclear quadrupole resonance (NQR) Spectrum of ammonium nitrate is presented recorded using two double resonance techniques – double contact cross relaxation and zero field NQR. The spectra gave the quadrupole coupling constant (Qcc) and asymmetry parameter (η) values for the nitro of 611 kHz, 0.229 and that for the ammonium nitrogen of 242 kHz, 0.835. The three relaxation transition probabilities have been determined for both the nitro and ammonium nitrogen atoms. The bi-exponential relaxation times (T 1) were measured at 295 K. The values for nitro are 16.9 s and 10.5 s and that of the ammonium are 23.0 s and 16.4 s.
Y ōnuki - One of the best experts on this subject based on the ideXlab platform.
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nmr NQR study of the quadrupole orders in binary uranium palladium intermetallic compound
Journal of Magnetism and Magnetic Materials, 2007Co-Authors: T Fujimoto, Yoshinori Haga, Hironori Sakai, Y Tokunaga, S Kambe, Y ōnukiAbstract:Abstract We report the first experiment of nuclear quadrupole resonance (NQR) in UPd 3 , probed by Pd 105 nuclei. In the normal state at 10 K, the four NQR lines at 32.25, 41.54, 54.51 and 67.36 MHz have been observed. From the obtained NQR Spectrum, the nuclear quadrupole frequency and the asymmetric parameter are deduced.
Alarich Weiss - One of the best experts on this subject based on the ideXlab platform.
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NQR study of [(CH3)2NH2]3InBr6 and [4-ClC5H4NH]2InBr5(H2O)
Journal of Molecular Structure, 1995Co-Authors: Hideta Ishihara, Hiromi Nishi, Alarich WeissAbstract:Abstract 81 Br, 115 In, and 35 Cl NQR spectra of dimethylammonium hexabromoindate(III)( 1 ) and 4-chloropyridinium pentabromoindate(III) monohydrate ( 2 ) were studied as a function of temperature. The 81 Br NQR Spectrum of 1 is a quartet with frequencies (MHz, 298K) 55.93, 71.90, 72.04 and 78.26, and an intensity ratio of 2:1:1:2. For 2 , five 81 Br NQR lines were found with frequencies (MHz, 298K) 74.09, 76.12, 84.52, 93.04 and 94.04. The intensities are equal. The 35 Cl NQR Spectrum of 2 is a doublet with frequencies (MHz, 298K) 35.50 and 35.72. The structure of the anions is deduced on the basis of the NQR results.
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Crystal Structure and 35Cl NQR of ( — ) β-(trichloromethyl)- β-propiolactone. Comparison with (±) β-(trichloromethyl)-β-propiolactone
Zeitschrift für Naturforschung A, 1993Co-Authors: Reha Basaran, Helmut Paulus, Alarich WeissAbstract:The crystal structure of (−)β-(trichloromethyl)-β-propiolactone at room temperature is reported, as is the 35 Cl NQR Spectrum in the range 77 ≤ T/K ≤ 323.5. The compound crystallizes with the space group D 2 4 − 2 1 2 1 2 1 , Z = 8, a = 2416.0 (10) pm, b = 975.6 (4) pm, c = 595.0 (2) pm. The intra-molecular distances and angles of the two crystallographically independent (#75) molecules in the unit cell are equal within the limits of error. The spread of the 35 Cl NQR Spectrum is within 600 kHz, not changing in the temperature range covered. The crystal structure and 35 Cl NQR Spectrum are discussed
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NQR and Crystal Structure of 4,5-Dichloroimidazole, C3H2N2Cl2
Zeitschrift für Naturforschung A, 1992Co-Authors: Alarich WeissAbstract:Abstract The two line 35Cl NQR Spectrum of 4,5-dichloroimidazole was measured in the temperature range 77≦ T/K ≦ 389. The temperature dependence of the NQR frequencies conforms with the Bayer model and no phase transition is indicated in the curves v ( 35Cl)= f(T). Also the temperature coefficients of the 35Cl NQR frequencies are "normal". At 77 K the 35Cl NQR frequencies are 37.409 MHz and 36.172 MHz and at 389 K 35.758 MHz and 34.565 MHz. The compound crystallizes at room temperature with the tetragonal space group D44-P41212, Z = 8 molecules per unit cell; at 295 K : a = 684.2(5) pm, c = 2414.0(20) pm. The relations between the crystal structure and the NQR Spectrum are discussed.
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79Br and 127I NQR of tert-Butylammonium Halides and Crystal Structure of (CH3)3CNH3⊕ Br⊖
Zeitschrift für Naturforschung A, 1992Co-Authors: Morteza Shabazi, Alarich WeissAbstract:Abstract The 79Br and the 127 I NQR Spectrum of tert-butylammonium bromide and iodide, respectively, was studied as a function of temperature. No phase transition was observed for the bromide in the temperature range covered. The 79Br NQR frequency is 9.056 MHz at 113 K and increases with increasing temperature (10.040 MHz at 293 K). The NQR Spectrum reveals a phase transition of ( CH3 ) 3 CNH⊕3I⊖ around 360 K with pronounced hysteresis. The nuclear quadrupole coupling constant of 127 I is 69.335 MHz with an asymmetry parameter of 0.154 for the high temperature phase at T = 370 K. For the low temperature phase the corresponding values are 67.136 MHz and 0.081 at 300 K. The crystal structure of tert-butylammonium bromide was studied at room temperature. The compound crystallizes orthorhombic, space group D152hPbca, with 4 formula units in the unit cell, a = 1832.1 pm, b = 918.5 pm, c = 899.8 pm. The crystal structure and hydrogen bond system are discussed in connection with the NQR results.
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Solid Phases from the Liquid System H2N(CH2)2NH2 ? CdBr2 ? HBr ? H2O. An X‐ray and 79,81Br — NQR Study of (H3N(CH2)2NH3)CdBr4, (H3N(CH2)2NH3) (CdBr3)2 · H2O, and (H3N(CH2)2NH3)2CdBr6
Berichte der Bunsengesellschaft für physikalische Chemie, 1991Co-Authors: V. G. Krishnan, Helmut Paulus, Alarich WeissAbstract:From the aqueous system ethylenediamine, (en), CdBr2 HBr H2O of varying component concentrations, at room temperature the compounds (enH2)CdBr4, (enH2)(CdBr3)2 · H2O, and (enH2)2CdBr6 were crystallized. 79,81Br NQR spectroscopy shows that the three solid phases, crystallized at room temperature, are the stable ones in the temperature range 77 ≤ T/K ≤ 300. (enH2)CdBr4 shows a three line 81Br NQR Spectrum, the frequencies lying in the range 53 ≤ v (81Br)/MHz < 68 and having negative temperature coefficients dv/dt over the whole temperature range covered. A phase transition with hysteresis is observed at 340 K. In the high temperature phase I only one 81Br NQR line is observed, with negative temperature coefficient, too. (enH2)(CdBr3)2 · H2O shows also a three line 81Br NQR Spectrum, the frequencies lying in the range 38 MHz to 72 MHz at room temperature with positive as well as negative temperature coefficients. (enH2)2CdBr6 reveals a four line 81Br NQR Spectrum, three of the lines lying in the range 40 MHz to 70 MHz; the fourth line was observed at frequencies as low as 10 MHz. (enH2)(CdBr3)2 · H2O crystallizes at room temperature monoclinic, space group C2h6-C2/c with Z = 4 (formula units per unit cell) a = 818 pm, b = 2413 pm, c = 801 pm, β = 107.8°. The structure is characterized by chains of units [Cd4Br12]4. The chains are built up by edge connected octahedra CdBr6 and the corners of two neighbouring octahedra are part of a bridging tetrahedron CdBr4, located alternating cis and trans on the chain. (enH2)2CdBr6 crystallizes also monoclinic, space group C2h2-P21/m, a = 669 pm, b = 2050 pm, c = 637 pm, β = 93.4°; Z = 4. The structure corresponds to a formulation ((enH2))2(CdBr4)2⊖ · 2Br⊖. In both compounds hydrogen bonding is observed. The NQR results are in full agreement with the crystal structures; structure and bond scheme are discussed.
Ismardo Bonalde - One of the best experts on this subject based on the ideXlab platform.
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14N NQR in 1,10-Phenanthroline and Dicyano bis(1,10-phenanthroline)iron(III)*
Zeitschrift für Naturforschung A, 1992Co-Authors: Juan Murgich, Yosslen Aray, Edgar Ospina Rico, Ismardo BonaldeAbstract:AbstractN NQR spectra of 1,10-phenanthroline and of dicyano bis(1,10-phenanthroline)iron(lll) were obtained at room temperature. An analysis based on the shifts of the NQR frequencies and in the topology of the charge distribution in a model (pyridine) showed that the complex formation produces a strong decrease in the N valence shell nonbonded maximum and an increase in the bonded density along each of the N - H bond directions. The NQR Spectrum showed that the complex formation produces only small changes in the charge distribution of the cyanide groups.
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the 14n NQR Spectrum and the crystal structure of ba fe cn 5no 3h2o at room temperature
Solid State Communications, 1990Co-Authors: Juan Murgich, Ismardo BonaldeAbstract:Abstract The previously reported 14N NQR Spectrum of the CN groups of Ba [Fe (CN) 5NO] · 3H2O (BNP) was shown to also contain lines of Na2 [Fe (CN) 5NO] · 2H2O used in the preparation of BNP. The number of NQR lines and their relative intensities in BNP confirmed that it has a Pbcm instead of a Pca21 space group at 293 K as previously assumed. The three CN sites found in BNP at room temperature are increased to five below 233 K and to eight below 131 K as a result of phase transitions. The effect on the NQR lines of the axial CN group of the disorder of some water molecules in BNP is also discussed.
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The 14N NQR Spectrum and the crystal structure of Ba[Fe(CN) 5NO] · 3H2O at room temperature
Solid State Communications, 1990Co-Authors: Juan Murgich, Ismardo BonaldeAbstract:Abstract The previously reported 14N NQR Spectrum of the CN groups of Ba [Fe (CN) 5NO] · 3H2O (BNP) was shown to also contain lines of Na2 [Fe (CN) 5NO] · 2H2O used in the preparation of BNP. The number of NQR lines and their relative intensities in BNP confirmed that it has a Pbcm instead of a Pca21 space group at 293 K as previously assumed. The three CN sites found in BNP at room temperature are increased to five below 233 K and to eight below 131 K as a result of phase transitions. The effect on the NQR lines of the axial CN group of the disorder of some water molecules in BNP is also discussed.
