High frequency paramagnetism

N moves towards high frequencies (paramagnetic shift) as Q increases and as or decreases. These results correct errors discovered in previous publications (A 28) (L 26). 

Ramsey obtained ay, by first-order and op by second-order perturbation theory (76) variational treatments give similar results (14, 71, 73). The term wp is sometimes called the second-order paramagnetic term and sometimes the high-frequency term (14), because of the dependence of the (temperature-independent) paramagnetism in molecules on the high-frequency matrix elements of the orbital moments (91). 

A review has been given on paramagnetic resonance spectroscopy of metal centers. It comprises both paramagnetic NMR as well as high frequency EPR methods applied mostly to copper proteins of the blue type but also to iron and manganese containing proteins.42... 

The carbide atom in 1 is located in the center of the square face such that it is partially exposed whereas the carbide atom in 2 is completely encapsulated by the six ruthenium atoms. From a spectroscopic viewpoint, carbide atoms are very distinctive and the earlier reviews have dealt with these aspects in detail.7 8 The IR spectrum of 1 contains peaks at 701 (s) and 670(m) cm 1, and 2 contains peaks at 717(sh), 703(s), 680(m), and 669(m) cm-1.22 I3C-NMR spectra of 1 and 2 do not appear to have been reported. This is probably due to the low yields in which these compounds were initially obtained at a time when, 3C-NMR was still not in widespread use in cluster chemistry. In general, the 13C-NMR resonance of carbide atoms ranges from 8 250 to 500. The high frequency resonances exhibited in 13C-NMR spectra reflect the different diamagnetic and paramagnetic effects experienced by a nucleus in such an unusual chemical environment.23... 

Sx, Sy, and Sz are the three components of the spin operator, D and E are the anisotropy constants which were determined via high-frequency electron paramagnetic resonance (D/kB 0.275 K and E/kB 0.046 K [10]), and the last term of the Hamiltonian describes the Zeeman energy associated with an applied field H. 

Cossee and Van Arkel (133) have pointed out that tetrahedral-site Co2+ does not obey a Curie-Weiss law in the paramagnetic region because the triplet Ts and r4 levels, which are at distances of only 4000 cm-1 and 7000 cm-1 from the singlet ground state r2 (see Fig. 12), introduce a measurable high-frequency, temperature-independent component into Xm that is given by equation 17. 

Moebius, K. (Ed.). (2001) High-Field and High-Frequency Electron Paramagnetic Resonance. [In Appl. 

The presence of paramagnetic anions in dilute solutions of diamagnetic cations manifests itself in the NMR spectra of the latter as resonance shifts and/or line broadenings. Such effects have been attributed to ion pair formation. Isotropic shifts due to ion pair formation are often, but not invariably (see below), predominantly dipolar in origin. Walker et al (257,258) have measured such shifts for some penta- and hexa-nitratolanthanate(iii) complexes of formulae [R4N]2Ln(N03)s, [R -py-R]2Ln(N03)5, and [R4N]2Ln(N03)e. The shifts are to high frequency for all complexes except Tm and Yb complexes which show strong low frequency shifts. 

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