engleski

Dielectric resonator-based resonant structure for sensitive ESR measurements at high hydrostatic pressures

We present a newly developed microwave probe head that accommodates a gasketed sapphire anvil cell (SAC) for performing sensitive electron spin resonance (ESR) measurements under high-hydrostatic pressures. The system was designed around commercially available dielectric resonators (DRs) having the dielectric permittivity of 30. The microwave resonant structure operates in a wide-stretched double-stacked geometry and resonates in the lowest cylindrical quasi TE_011 mode around 9.2 GHz. The most vital parts of the probe’ s microwave heart were made of plastic materials, thus making the resonant structure transparent to magnetic field modulation at 100 kHz. The overall ESR sensitivity of the probe was demonstrated for a small speck of 2, 2-diphenyl-1-picrylhydrazyl radical (DPPH) positioned in the gasket of the SAC, using water as the pressure-transmitting medium. The system was also used for studying pressure-induced changes in spin-relaxation mechanisms of a quasi-1D-conducting polymer, K_1C_60. For small samples located in the sample hole of the gasket the probe reveals sensitivity that is only about 3 times less than that yielded by regular ESR cavities.

CW-X-band ESR; Dielectric resonator; High-hydrostatic pressure; Sapphire anvil cell

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