Progress Towards a Higher Sensitivity ¹³C-Optimized 1.5 mm HTS NMR Probe

Nuclear magnetic resonance (NMR) probes using thin-film high temperature superconducting (HTS) resonators offer high sensitivity and are particularly suitable for small-sample applications. We are developing an improved 1.5 mm HTS NMR probe designed for operation at 14.1 T and optimized for ¹³C detection. The total sample volume is about 35 μL and the active sample volume is 20 μL. The probe employs HTS resonators for ¹³C and ¹H transmission and detection and the ²H lock. We examine the interactions of multiple superconducting resonators and normal metal tuning loops on coil resonance frequency and probe sensitivity. We test a recently introduced ¹³C resonator design, engineered to significantly increase ¹³C detection sensitivity over previous all-HTS probes. At zero field, we observe a ¹³C quality factor of 6000 which is several times higher than previous resonators. In this work the coil design considerations and probe build-out procedure are discussed.