ZfN: Search Results

1	Author	Nicolai Sinyavsky, Michal Ostafin, Mariusz Maćkowiak	Requires cookie*
	Title	Rapid Measurement of Nutation NQR Spectra in Powders Using an RF Pulse Train
	Abstract	The method of two-dimensional nutation NQR spectroscopy, introduced by Harbison in 1989, has been successfully used for determining of the asymmetry parameter of the EFG tensor for spin-3/2 nuclei in both powdered and monocrystal samples in the absence of an external magnetic field. The inconvenience inherent in the method, however, is the long time required, because data acquisition must be repeated for various RF pulse lengths. We discuss a method to reduce the time of the nutation experiment by using a sequence of identical short RF pulses of length r w and distance t. It is shown that for an NQR frequency co 0 , frequency offset Aco, and pulse parameters satisfying the relation co 0 1 -I-Aco t w = 2 n k (k = 1, 2, 3,..., n) a synchronism of pulse action takes place and the nutation interferogram can be measured "stroboscopically" between the pulses. The maximum time saving factor that can be obtained as compared to the conventional nutation experiment is of the order of the number of pulses used in a pulse train. The method has been successfully applied for determination of the asymmetry parameter for one of the two 35 C1 sites in polycrystalline 2,4,6-trichloro-l,3,5-triazine (cyanuric chloride).
	Reference	Z. Naturforsch. 51a, 363—367 (1996); received February 13 1996
	Published	1996
	Keywords	Nuclear quadrupole resonance, Two-dimensional nutation spectroscopy, Asymmetry parameter
	Similar Items	Find
	DEBUG INFO
	TEI-XML for	default:Reihe_A/51/ZNA-1996-51a-0363.pdf
	Identifier	ZNA-1996-51a-0363
	Volume	51

2	Author	David Stephenson, JohnA S Smith, St Augustine, Tobago Trinidad	Requires cookie*
	Title	Double Resonance Detection Using Zero Field Level Crossing
	Abstract	Double resonance level crossing detection cannot normally be used to record transitions between the quadrupole Zeeman levels. Neither can it be used if the quadrupole resonance frequency is larger than the proton NMR frequency in high field. A simple variation of the level crossing experiment is demonstrated which allows energy to be efficiently transferred from quadrupole to proton system and hence lead to detection in these two cases. In the case of the quadrupole Zeeman levels it allows transitions between the ±\ levels to be detected in a small magnetic field, allowing measurement of the asymmetry parameter (r\) for spin 3/2 systems. This is demonstrated for the 1X B nucleus in triethanolamine borate. Detection of high frequency quadrupole transitions is demonstrated from which relaxation information is obtained.
	Reference	Z. Naturforsch. 53a, 301—304 (1998); received October 31 1997
	Published	1998
	Keywords	NQR, Asymmetry Parameter, Relaxation, n B, 35 C1
	Similar Items	Find
	DEBUG INFO
	TEI-XML for	default:Reihe_A/53/ZNA-1998-53a-0301.pdf
	Identifier	ZNA-1998-53a-0301
	Volume	53

3	Author	ValentinP. Feshin, ElenaV. Feshina	Requires cookie*
	Title	Correlation between the 35 CI NQR Parameters of Chloro-containing Organic and Organometallic Compounds and the Results of ab initio Calculations
	Abstract	The results of comparison of experimental 35 C1 NQR parameters for a great number of organic and organometallic compounds and estimated ones using ab initio calculations at the RHF/6-31G(d) level were systematized. The NQR frequency changes on going from one compound to another depend, in general, on the changes of populations of the CI atom p"-orbitals in these compounds and, first of all, of populations of their less diffuse parts.
	Reference	Z. Naturforsch. 55a, 555—559 (2000); received December 15 1999
	Published	2000
	Keywords	ab initio Calculations, p-orbital Populations, 35 C1 NQR Frequency, Asymmetry Parameter, Chloro-containing Organic and Organometallic Compounds
	Similar Items	Find
	DEBUG INFO
	TEI-XML for	default:Reihe_A/55/ZNA-2000-55a-0555.pdf
	Identifier	ZNA-2000-55a-0555
	Volume	55