HyReSpect: A broadband fast-averaging spectrometer for nuclear magnetic resonance of magnetic materials

We announce the successful development of a homemade frequency-swept nuclear magnetic resonance (NMR) spectrometer entirely designed and built at the University of Parma, optimized for the study of magnetic materials but also offering good performance as a general-purpose instrument for solid-state NMR. The spectrometer features heterodyne-based pulser and receiver with four-quadrant phase shifting and quadrature detection; a 150 MHz digital signal processor as a digital pulser for timing and control functions, capable of triggering events with a resolution of 6.6 ns; a two-channel 12 bit 25 MS/s digitizer hosted by a personal computer; and a graphical user interface control program running under Linux, which also integrates external field and temperature controls. The receiver exhibits a flat response from 8 up to 670 MHz, a frequency span suitable for the investigation of magnetic transition metal compounds (V, Co, Mn, Cu), and intrinsic dead time of less than 2 mu s, as required with the fast-relaxing NMR signals often encountered in magnetic materials. The rf design employing only one external signal generator, and the fast-averaging performance of the system (more than 10 000 repetitions per second), are probably the most remarkable features of our apparatus. (c) 2005 American Institute of Physics.