Digitally Based Precision Time-Domain Spectrometer for NMR Relaxation and NMR Cryoporometry

NMR Relaxation (NMRR) is an extremely useful quantitative technique for material science, particularly studying polymers and porous materials. Cryoporometry (NMRC) a powerful the measurement of pore-size distributions total porosities. This paper discusses use, capabilities application newly developed compact time-domain relaxation spectrometer suitable both solid liquid samples (Mk3 & Cryoporometer, Lab-Tools (nano-science), Ramsgate, Kent, UK. (2019)). highly precision Spectrometer based on Field Programmable Gate array (FPGA) module custom surface mount low-noise receiver linear transmitter. A high proportion RF circuitry in digital form, implemented as firmware FPGA, which gives instrument excellent long-term stability. It also includes on-chip Linux computer. The FPGA credit-card sized, transmitter are even smaller. software, including top-level pulse sequence definitions, written processing language, Apl. comes complete with Graphical User Interface (GUI) control on- offline curve fitting data analysis. recent development Peltier thermo-electrically cooled variable-temperature (V-T) probe that cools sample below −60 °C discussed. cooling temperature smoothness needed by (10 mK near bulk melting point). enables NMRC materials, unusually wide range sub-nano to over 1 micron-sized pores. Spectrometer’s small size, ability measure solids, low noise performance make it science studies field university, research institute, company school laboratories. human portable version now exists. Use controlling GUI described, results from example Cryoporometric measurements given.