An automated instrument for polarization-enhanced broadband nuclear quadrupole resonance (NQR) spectroscopy.

An automated instrument for improving the sensitivity of nuclear quadrupole resonance (NQR) spectroscopy is presented. The device is capable of pre-polarizing samples within a custom Halbach-type permanent magnet and then moving them into an external probe for zero-field NQR detection. Polarization transfer between protons and nitrogen (N) nuclei in the sample occurs during demagnetization, thus increasing the amplitude of the detected NQR signals. The sample motion profile is completely programmable, thus providing a high level of control over the sample position and velocity for optimizing the polarization transfer process for various samples. Moreover, the magnet and motion controller are combined with a shielded sample probe and ultra-broadband front-end electronics (both designed in-house) to realize a complete scientific instrument for N NQR experiments. Compared with previous work in the field, the system is designed to be programmable, robust, and easy to use. Experimental results from several samples are also presented.