2 3 Na two-dimensional nutation N M R was applied to N a t + *Zr 2 Si v P 3 _ v O, 2 with x = 0, 1, and 2. The nutat ion spectrum in each compound consists of two clearly separated peaks corresponding to the two crystallographically inequivalent sodium sites. In the compound with x = 2 the nuclear quadrupole coupling constants (e Qq/h) and the asymmetry parameters (rj) were by spectral simulati...

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 ...

Two NMR techniques, zH MAS NMR and echo Fourier 27AI NMR, have been applied for the first time to the investigation of Bronsted sites in dehydrated hydrogen forms ofzeolites. The “AI signal of SiOHAl sites, which was “NMR-invisible” until now, yields a quadrupole coupling constant C,,= 16 MHz for the dehydrated zeolite H-ZSM-5. The values of C,, determined from the ZH MAS NMR spectra of SiODAl ...

Temperature dependences of 35C1 and 2H quadrupole coupling constants and 35C1 NM R spin-lat­ tice relaxation times in polycrystalline samples were measured in the rotator phase of the butylam­ monium chlorides C4H 9N H 3C1 and C4H 9N D 3C1, obtainable above the phase transition tempera­ ture of 241 K. A rapid decrease of the quadrupole coupling constants of both nuclei upon heating is attribute...

Simulations of solid-state Si N M R spectra in nitrogen-containing silicon ceramics and glasses are described. The range of SiN ; t04 ._x tetrahedra is covered, with emphasis on the experimental conditions needed to observe the effect of the incompletely averaged Si, 1 4 N dipolar coupling. A simple equation is discussed concerning its use in the interpretation of these Si spectra, including th...

Zeeman C1 NQR spectroscopy has been applied to determine the magnitude and orientation of the E F G tensors at the chlorine sites in a single crystal of (CH 3 NH 3 ) 2 [ (C 2 H 5 )SnCl 5 ] at 293 K. The assignment of the N Q R frequencies v ;(Cl), the corresponding quadrupole coupling constants e Q f P ^ h ^ 1 , and the asymmetry parameters f/,(C 1) to certain Cl' atoms is discussed. The most p...

In this work, the calculated nuclear quadrupole coupling constants of O in some styrylquinoline conformers were presented. The calculations were carried out to find the relationships between the charge distribution of styrylquinolines and their pharmaceutical behavior and to explore the differences among the electronic structures of some conformers of these potent HIV IN inhibitors. Furthermore...

Hyperfine quantum-beat spectroscopy has been utilized in a pump-probe configuration to measure magnetic dipole (A) and electric quadrupole (B) coupling constants in the 3d D3/2 and 3d D5/2 levels of three isotopes of potassium. For many of these levels, the largest hyperfine splitting is smaller than the natural width, and so a subnatural linewidth technique is required. In the experiments, the...

A mean-field theory for the ordering of hydrogen molecules on a triangular net is derived in terms of the quadrupole coupling constant Γ, the crystal field Vc, and the temperature T. The phase diagram consists of six regions, separated by firstand second-order transitions. For almost all values of Vc/Γ for which ordering occurs, the disordered to ordered phase transition is continuous. At T=0 K...

Nuclear electric quadrupole coupling constants e2qQ/h have been obtained b y evaluation o f quadrupole perturbations in 5 1 V N M R spectra of various vanadyl esters and esterchlorides of the general formula V O C l 3 _ „ ( O R ) n («, = 0 3 ; = Me, Prra, Pr*, B u » and Bu«). e2qQlh values have been calculated from (i) 2nd. order quadrupole splittings of the 5 1 V N M R signals in pseudopolycra...