NMR Instrumentation...
Since the middle 1980´s, LEAR team has been dedicated to the construction/mounting of NMR spectrometers and accessories.
The first step was to set up a high-resolution solid-state NMR spectrometer, initially with the development of rf transmitters and receivers, signal digitizer/averager, pulse programmer, double-resonance probes, magic-sample spinning system, fast-Fourier-transform software, and using a wide room-temperature bore (30-cm diameter) Oxford 2 T superconductor magnet. Later on, we acquired a Libra Tecmag console and a MAS-double resonance Doty probe. By the second half of the 1980´s we were running the CP/MAS/Decoupling variable temperature experiments routinely. Since then, our routine has been to use commercial equipment, especially Tecmag consoles, in conjunction with accessories developed in the LEAR group. Currently, we are focused on the development of time-domain NMR systems dedicated to the study of porous media, with special attention to the oil reservoir rocks, for magnetic fields ranging from 0.01 to 10 T. To this end, we are developing appropriate probes for experiments dedicated to measures of relaxation times (T1 and T2) and diffusion coefficients (D), as well as their correlations (T1-T2, T2-T2 and D-T2). These probes are being used in conjunction with conventional resistive, permanent and superconducting magnets. For the same purpose, are also developing our own Inverse Laplace Transform softwares. Recently, we finished the assembly of two Porous Media NMR equipment, equipped with a Redstone console and a 2 T permanent magnet, both from Tecmag, and probes designed and built in our lab, including one for studying live-oil and oil-saturated rocks under reservoir conditions (~10.000 psi and ~100 C). One of these two NMR systems is installed at CENPES/Petrobras and the other one in LEAR. More recently, we began the assembly of a single-sided magnet-based spectrometer, in partnership with Prof. Dimitrios Sakellariou, and a low-field DNP system. Although we continue to use Tecmag consoles, we have begun building a new NMR system in partnership with the Brazilian company Fine Instrument Technology - FIT. |