نتایج جستجو برای: طیفسنجی nqr

تعداد نتایج: 652  

2012
Yasumasa Tomita Koji Yamada Hiroshi Ohki Tsutomu Okuda

Li3InBr6 and NaInBr4 have been synthesized and characterized by means of DTA, 8 'Br NQR, Li, Li, Na, and l l In NMR, and AC conductivity. These measurements revealed the presence of phase transitions and cationic diffusion in both compounds. From the spin-lattice relaxation times of 1 Br NQR and the peak widths of Li and Na NMR spectra, it is deduced that the conduction is due to cationic diffu...

2012
Rama Basu

NQR studies o f a number of molecular complexes with p-chloronitrobenzene and o-chloronitrobenzene as acceptors and different hydrocarbons as donors were carried out. A linear relationship between the NQR shift and the ionization potentials o f the donors is obtained. Maksyutin’s idea o f a positive shift with respect to acceptors having a quadrupolar nucleus is shown to hold in those systems. ...

1999
P. C. Hammel

La nuclear quadrupole resistance ~NQR! and relaxation measurements in lightly hole-doped La1.82xEu0.2SrxCuO4 have been used to investigate the microscopic properties of the low-temperature orthorhombic to low-temperature tetragonal transition. The transition is characterized by a sharp peak in La NQR relaxation rate, indicating phonon softening. We find that the structural phase transition is a...

Journal: :Physical review letters 2002
P M Singer A W Hunt T Imai

We report experimental evidence for the spatial variation of hole concentration x(hole) in the high T(c) superconductor La2-xSrxCuO4 ( 0.04 < or = x < or = 0.16) via 63Cu NQR using 63Cu isotope enriched samples. We demonstrate that the extent of the spatial variation of the local hole concentration Delta(x)hole is reflected on (63)1/T1 and deduce the temperature dependence. Delta(x)hole increas...

2000
V. S. S. Sastry K. Venu S. Uma Maheswari R. K. Subramanian

Dynamic processes in solids exhibiting structurally incommensurate phases are briefly reviewed, and the application of NMR and NQR is discussed. The unique utility of these methods, arising due to, on one hand, the microscopic resonant nature of the probe used and, on the other, the presence of periodic, though incommensurable, structure , is brought out by presenting recent results in a protot...

Journal: :Chinese Physics Letters 2021

We report $^{121/123}$Sb nuclear quadrupole resonance (NQR) and $^{51}$V magnetic (NMR) measurements on kagome metal CsV$_3$Sb$_5$ with $T_{\rm c}=2.5$ K. Both NMR spectra NQR split after a charge density wave (CDW) transition, which demonstrates commensurate CDW state. The coexistence of the high temperature phase between $91$ K $94$ manifests that it is first order transition. At low temperat...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه تربیت معلم تهران 1379

طیف سنجی رزونانس چهارقطبی هسته یکی از مفیدترین روشها در تعیین توزیع الکترونی و شناسایی ترکیبات شیمیایی میباشد. در این پروژه جمعیت الکترونی اربیتالهای py و pz اتم ید در تعدادی از ترکیبات آلی و معدنی یددار با استفاده از معادلات و مقادیر تجربی فرکانس nqr و پارامتر ضدتقارن بدست آمده است و با جمعیت الکترونی اربیتالهای py و pz محاسبه شده به روش pm3 مقایسه شده است . همچنین پارامترهای nqr هسته ید (i 5/...

Journal: :Journal of Molecular Structure 1980

Journal: :Journal of Physics: Conference Series 2011

2013
S. Günther P. G. Schrade

The quadrupole coupling constants in solids usually depend on temperature (see f.e. Ref. [1 — 8 ]). This can be explained by the change of vibration amplitudes of molecules, but the influence of the volume expansion on the electric field gradient has also to be taken into account [4], For 185Re and 187Re in some peirhenates NQR measurements have been reported [9 — 16]. With the exception of NH ...

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