Nuclear quadrupole resonance spectroscopy NQRS

The third problem also concerns the choice of whether to leave out certain material. In a book of this size it is not possible to cover all branches of spectroscopy. Such decisions are difficult ones but I have chosen not to include spin resonance spectroscopy (NMR and ESR), nuclear quadrupole resonance spectroscopy (NQR), and Mossbauer spectroscopy. The exclusion of these areas, which have been well covered in other texts, has been caused, I suppose, by the inclusion, in Chapter 8, of photoelectron spectroscopy (ultraviolet and X-ray), Auger electron spectroscopy, and extended X-ray absorption fine structure, including applications to studies of solid surfaces, and, in Chapter 9, the theory and some examples of lasers and some of their uses in spectroscopy. Most of the material in these two chapters will not be found in comparable texts but is of very great importance in spectroscopy today. 

Nuclear quadrupole resonance spectroscopy (NQR) is a very direct and experimentally quite simple method for studying the interaction between the electric quadrupole moment of a nucleus and the electric field gradient at its site. Since the discovery of the method by Dehmelt and Kruger 3>6) in 1950, a large amount of experimental material has been collected, most of which has been interpreted within the frame of semiempirical theories. 

Other evidence for covalence in transition metal complexes has been obtained from nuclear magnetic resonance spectroscopy (NMR), electronic spectroscopy, nephelauxetic effects, and nuclear quadrupole resonance spectroscopy (NQR) and from the detailed magnetic properties of such complexes. Thus, without giving a detailed description of each of these effects (which is beyond the scope of this book), it can be stated unequivocally that considerable physical evidence shows the existence of some degree of covalence in transition metal complexes. 

T. P. Das and E. L. Flahn, Nuclear Quadrupole Resonance Spectroscopy (Supplement 1 in the series Solid State Physics) Academic Press, New York, 1958, The classic early work on NQR theory. 

Whilst diffraction techniques immediately spring to mind for solid samples, the quadrupolar nature of the heavier halogen nuclei means that a principle technique related to SS NMR spectroscopy is nuclear quadruple resonance spectroscopy.6 For systems with a quadrupole moment, an EFG generates two energy states in the absence of an applied magnetic field.3/7 It is appropriate to start by considering illustrative cases in which SS NMR spectroscopy provides information that the closely related nuclear quadrupolar resonance (NQR) technique does not. 

G. P. Wulfsberg, Nuclear Quadrupole Resonance (NQR) Spectroscopy, in Encyclopedia of Inorganic Chemistry, 2nd edn, (R. B. King ed.), John Wiley Sons, Ltd., Chichester, UK, 2008. 

With the help of 35C1 Nuclear Quadrupole Resonance (NQR) spectroscopy and AMI, MNDO h PM3 calculation data of tautomers of 2-trichloromethyl-5(6)-nitrobenzimidazole it is established that 5-nitro tautomer is more preferable than its 6-isomer (Scheme 3.76) [1407],... 

Magnetic Circular Dichroism (MCD) Spectroscopy Nuclear Magnetic Resonance (NMR) Spectroscopy of Metallobiomolecules Nuclear Quadrupole Resonance (NQR) Spectroscopy Electron Spin Echo Envelope Modulation (ESEEM) Spectroscopy. 

No N nuclear quadrupole resonance (NQR) studies have been reported for transition metal nitrosyl complexes. This technique is expected to show interesting differences between linear and bent nitro-syls since the values of the quadrupole coupling constant and the asymmetry parameter depend on the relative populations of the nitrogen s,p, py, andpz orbitals. NQR spectroscopy has been used to study organic and inorganic nitroso compounds, and it is found that both... 

R262 K. P. J. Braun, W. P. Vandertop, R. H. J. M. Gooskens, K. A. F. Tulleken and K. Nicolay, NMR Spectroscopic Evaluation of Cerebral Metabolism in Hydrocephalus A Review , Neurol Res., 2000,22, 51 R263 P. J. Bray, C. Nuclear Quadrupole Resonance (NQR) Studies of Glass Structure , Ser. Dir. Condens. Matter Phys., 2000,17,249 R264 L. Brecker and D. W. Ribbons, Biotransformations Monitored in Situ by Proton Nuclear Magnetic Resonance Spectroscopy , Trends Bio-technol, 2000,18,197... 

The most important experimental techniques in this field are structural analyses by both X-ray and neutron diffraction methods, and infrared and Raman spectroscopic measurements. Less frequently used techniques are nuclear magnetic resonance, both broad band NMR spectroscopy and magic angle spinning methods (MAS), nuclear quadrupole resonance (NQR), inelastic and quasielastic neutron scattering, conductivity and permittivity measurements as well as thermal analyses such as difference thermal analysis (DTA), differential scanning calorimetry (DSC), and thermogravimetry (TG and DTG) for phase transition studies. 

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