ESR and ENDOR experiments using a disc-shaped resonator working in the Whispering Gallery Mode (WGM)

Abstract

Abstract. Different instrumental apparatuses are presented employing disc-shaped dielectric resonators working in the Whispering Gallery Mode (WGM). The conditions suitable to take the best ffom the microwave power obtalrled from a trade klystron in the X-band have been verified for the ESR part of the experiments. It is well known that a good ESR saturation condition is an essential prerequisite to have satisfactory ENDOR results. The WGM dielectric resonators seem to be very suitable for multiple irradiation purposes and in particular for ENDOR experiments which is the aspect we wanted to exploit here. Various radiofrequency ENDOR irradiation circuits have been tested and the obtained spectra of a y-irradiated single crystal are presented and criticized. Some results for very high frequency ESR applications are also reported.

A wide-band Whispering Gallery Mode dielectric resonator having multiple high-Q cavities for high-field ESR spectroscopy

“…The peculiarities and the advantages of the Whispe¡ Gallery Mode (WGM) with respect to the usual TE and TM distributions of the electromagnetic fields when dealing with dielectric resonators for ESR spectroscopies have already been put in evidente, at least with respect to some applications [1,2]. These studies explored particularly the behaviour of large disc-shaped dielectric resonators (radius of the order of 40 mm) working in the WGM in the commonly used X-band from 9 to 10 GHz.…”

“…These high Q-values can be obtained also in the total absence of metal walls or screens around the resonator which are usually necessary when TE or TM dielectric resonators are considered. The total absence of metallic parts renders the WGM component an ideal one for multifrequency irradiation experiments like ENDOR [2], LODESR [3] and many other non-linear spectroscopies. The results here resumed are to be ascribed both to the total transparency of the WGM dielectric resonator to electromagnetic fields with which it is not in resonance and to its self-confinement properties.…”

“…n (1) a~-[(~~~~ As it has already been shown [1,2], the value of the angle of incidence 0 determines the extent of the self-confinement and hence the value of Q. The inherent losses of the material building-up the resonator are the only other parameter controlling the value of Q.…”

Simultaneous Micromechanical and Electromagnetic Detection of Electron Paramagnetic Resonance

“…Whispering gallery dielectric resonators have been used in the past few years for EPR applications (12)(13)(14). These resonators have several appealing characteristics that can be summarized here.…”

High-Field, Multifrequency EPR Spectroscopy Using Whispering Gallery Dielectric Resonators

“…A series of works (22)(23)(24) showed the capabilities of this type of resonators in EPR experiments carried out at different frequencies up to 75 GHz.…”