Electron Paramagnetic Resonance in Irradiated CsCl

Abstract

Two paramagnetic species have been observed in CsCl after irradiation at low temperatures with 2-Mev electrons. One of these, an anisotropic, "hole"-type center, has not yet been positively identified. The resonance signal from the other center has all the properties expected of the CsCl F center. The F-center parameters are g= 1.984±0.001, A =49.5±1.0 gauss, and the envelope width at half maximum is approximately 800 gauss. The partially resolved hyperfine lines due to the nearest-neighbor Cs nuclei have an estimated width at half maximum of 17±5 gauss. Due to the low signal-to-noise ratio only 38 of the expected 57 lines have been observed.

An electron - nuclear double-resonance study of the F centre in CsBr

“…The value of a/ h = 130.3 MHz for the isotropic part of the Cs I hyperfine interaction is similar to the value of 140 MHz for the F centre in CsCl [3]. In addition, the aand b-values agree very well with theoretical values for CsBr calculated by Harker [5] (a th /h = 157 MHz; b th /h = 5.8 MHz).…”

“…In CsBr only a broad unresolved EPR line at g = 1.996 with a peak-to-peak derivative linewidth of 70 mT has been detected, indicating a fairly large superhyperfine (shf ) interaction with the neighbouring Cs nuclei [2]. In CsCl the EPR spectrum shows structure due to shf interactions with the nearest Cs neighbours [3]. As a basis for any model of the E-V transfer mechanism, a more detailed study by means of electron-nuclear double-resonance (ENDOR) is necessary, which we present for CsBr in this communication.…”