Advanced Product Development

Cryo-MAS Probe

HR NMR probes for liquids have recently become available with cryogenically cooled sample coils that promise major advances in the field of NMR owing to their factor of four improvement in SNR.  Even greater improvements in SNR may be possible in High-Resolution (HR) Magic Angle Spinning (MAS) , which extends NMR techniques to inhomogeneous systems, such as human and animal tissues, and solids.

The goal of this major, long-term development effort is to ultimately achieve an order of magnitude gain in S/N in HR-MAS variable temperature (VT) NMR probes for NMR spectroscopy of inhomogeneous systems and many solids. Cryo-coil probes achieve their improvement in SNR from the combined effects of reduced noise temperature and improved Q, in spite of their reduced magnetic filling factor. In addition to improved S/N for samples near RT, the CryoMAS probe may ultimately allow the sample VT range to extend from 30 K to 400 K while the RF coils and capacitors are kept at ~25 K.

The engineering challenges of developing a CryoMAS probe (HR-MAS with full-range VT capability and Magic Angle Gradient) are substantial but not insurmountable. Preliminary circuit analyses show that a combination of (1) a novel approach to quad-resonance MAS ( ¹H- ¹³C- ²H- ¹⁵N) with all of the critical circuit elements maintained at ~25 K, (2) integrating a ceramic dewar into a novel sample spinner design, and (3) cryogenic preamps, offers the potential for an order of magnitude increase in SNR in an MAS probe for many applications.  Hence, signal-averaging time may be reduced by up to two orders of magnitude.  The extended cryogenic sample range of the probe will permit further gains in SNR for many solids applications.

We report our progress toward demonstrating feasibility of a dewared 3 mm MAS spinner design with a high-efficiency quad-resonance cryogenic circuit for use at fields up to 800 MHz. Please see our latest technical poster on:

Development of a CryoMAS HR-MAS-MAG NMR probe for High-field WB magnets,
presented at ENC 2005, Providence, Rhode Island, USA.