Multi-frequency high-field methods

Analysis of the spectra at different frequencies yielded the parameters D = — 2.20(5) cm-1, = 0.0(1) cm-1, and a nearly isotropic g-factor, g = 1.98(2), none of which could have been determined at X-band. Analysis was aided by the observation of different slopes of the B vs. v plots for Ams > 1 and Ams = 1 transitions. A review of advanced methods, including high-field EPR, is given in ref. 11. Various recent applications of high field and multi-frequency EPR are described in refs 19-31. 

The advances in technology in the last years led to the development and optimization of new ESR methods such as high field/multi-frequency ESR [29-31], double resonance [32, 33], and pulse methods [34-36]. The improvements in resolution brought by these methods have made possible analysis and interpretation of more complex systems and detection and characterization of transient paramagnetic intermediates inaccessible before. 

Buryakov, I.A. Krylov, E.V. Nazarov, E.G. Rasulev, U.K., A new method of separation of multi-atomic ions by mobility at atmospheric pressure using a high-frequency amplitude-asymmetric strong electric field, Int. J. Mass Spec. Ion Proc. 1993,128,143-148. 

An important aspect in control schemes based on the Stark effect is the choice of the frequency of the control field. It should be chosen such as to ensure a non-resonant interaction with the molecule. In our case, as mentioned in Sect.7.2.1, all the elements of the dipole moment matrix along the z direction are zero by symmetry. However, two-photon transitions between the Si and S2 states can be mediated by the non-zero af2(Q) matrix element. A value of hujc = 1-8 eV, which is high with respect to any two-photon transition between the Si and S2 states was chosen. Calculations with peak intensities of 0,10, 20,30,40 and 50 TW/cm for the control field were performed. The peak intensity of the pump pulse was set to 0.2TW/cm. In order to address various parts of the spectmm, three different photon energies (4.6,4.7 and 4.8 eV) were considered. The TDSE of Eq. (7.27), for each set of parameters was solved using the MCTDH method in the multi-set formalism. In each... 

Advanced EMR methods may be used to conduct quantitative measurements of nuclear hyperfine interaction energies, and these data, in turn, may be used as a tool in molecular design because of their direct relation to the frontier orbitals. The Zeeman field dependence of hyperfine spectra enables one to greatly improve the quantitative analysis of hyperfine interaction and assign numeric values to the parametric terms of the spin Hamiltonian. Graphical methods of analysis have been demonstrated that reduce the associated error that comes from a multi-parameter fit of simulations based on an assumed model. The narrow lines inherent to ENDOR and ESEEM enable precise measures of peak position and high-resolution hyperfine analyses on even powder sample materials. In particular, ESEEM can be used to obtain very narrow lines that are distributed at very nearly the zero-field NQI transition frequencies because of a quantum beating process that is associated with... 

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