Q-band EPR cryoprobe

Following the success of cryogenic EPR signal preamplification at X-band, we present a Q-band EPR cryoprobe compatible with a standard EPR resonator. The probehead is equipped with a cryogenic ultra low-noise microwave amplifier and its protection circuit that are placed close to the sample in the same cryostat. Our cryoprobe maintains the same sample access and tuning which is typical in Q-band EPR, as well as supports high-power pulsed experiments on typical samples. The performance of our setup is benchmarked against that of existing commercial and home-built Q-band spectrometers, using CW EPR and pulsed EPR/ENDOR experiments to reveal a significant sensitivity improvement which reduces the measurement time by a factor of about 40× at 6 K temperature at reduced power levels

Baltic labour in the crucible of capitalist exploitation: reassessing 'post-communist' transformation

Thirty years after the fall of the Berlin Wall, this article re-assesses ‘post-communist’ transformation in the Baltic countries from the perspective of labour. The argument is based on a historical materialist approach focusing on the social relations of production as a starting point. It is contended that the uneven and combined unfolding of ‘post-communist’ transformation has subjected Baltic labour to doubly constituted exploitation processes. First, workers in Estonia, Latvia and Lithuania have suffered from extreme neoliberal restructuring of economic and employment relations at home. Second, migrant workers from Central and Eastern Europe in general, trying to escape exploitation at home, have faced another set of exploitative dynamics in host countries in Western Europe such as the UK. Nevertheless, workers have continued to challenge exploitation in Central and Eastern Europe and also in Western Europe, and have been active in extending networks of transnational solidarity across the continent

A sensitivity leap for X-band EPR using a probehead with a cryogenic preamplifier

Inspired by the considerable success of cryogenically cooled NMR cryoprobes, we present an upgraded X-band EPR probehead, equipped with a cryogenic low-noise preamplifier. Our setup suppresses source noise, can handle the high microwave powers typical in X-band pulsed EPR, and is compatible with the convenient resonator coupling and sample access found on commercially available spectrometers. Our approach allows standard pulsed and continuous-wave EPR experiments to be performed at X-band frequency with significantly increased sensitivity compared to the unmodified setup. The probehead demonstrates a voltage signal-to-noise ratio (SNR) enhancement by a factor close to 8× at a temperature of 6 K, and remains close to 2× at room temperature. By further suppressing room-temperature noise at the expense of reduced microwave power (and thus minimum -pulse length), the factor of SNR improvement approaches 15 at 6 K, corresponding to an impressive 200-fold reduction in EPR measurement time. We reveal the full potential of this probehead by demonstrating such SNR improvements using a suite of typical hyperfine and dipolar spectroscopy experiments on exemplary samples