A cryogenic receiver for EPR

作者：Narkowicz R^*; Ogata H; Reijerse E; Suter D

来源：Journal of Magnetic Resonance, 2013, 237: 79-84.

DOI：10.1016/j.jmr.2013.09.017

• Cryogenic receiver
• Planar microresonators
• Signal-to-noise ratio
• Sensitivity

Cryogenic probes have significantly increased the sensitivity of NMR. Here, we present a compact EPR receiver design capable of cryogenic operation. Compared to room temperature operation, it reduces the noise by a factor of approximate to 2.5. We discuss in detail the design and analyze the resulting noise performance. At low microwave power, the input noise density closely follows the emission of a cooled 50 Omega resistor over the whole measurement range from 20 K up to room temperature. To minimize the influence of the microwave source noise, we use high microwave efficiency (approximate to 1.1-1.7 mT W-1/2) planar microresonators. Their efficient conversion of microwave power to magnetic field permits EPR measurements with very low power levels, typically ranging from a few mu W down to fractions of nW.

• 出版日期2013-12