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NMR Spectroscopy
AT-PMSC-1 is an automatic tuning and matching system for NMR spectroscopy, consisting of a wideline research grade goniometer probe, detachable stepper motor drive unit, high/low power RF switch, and CompactPCI-based controller unit with touchscreen interface. It provides for automatic tuning of RF resonant circuits in NMR experiments with X-nuclei resonance frequencies up to 400 MHz. Its application areas span from wide line NMR of disordered solids where spectra are acquired using point-by-point frequency scan (frequency-stepping) methods, to investigations of smeared phase transitions via NMR of low-sensitivity nuclei or low concentration probes where detuning takes place due to temperature-dependent capacitance and inductance of the trimming elements of the NMR detection circuit.
AT-PMSC-1 is typically integrated into the RF detection circuit of the spectrometer by an in line connection of the remotely controlled RF switch, immediately in front of the probe. The RF switch is used to redirect the RF line of the NMR probe from the autotuning controller to the NMR spectrometer during the signal acquisition mode. In this way, operation of AT-PMSC-1 that is independent of spectrometer’s hardware is achieved; no RF or I/O connectivity between the spectrometer and AT-PMSC-1 is required.
Trimmer capacitors
The standard NMR detection circuit featuring an irradiation/detection coil and two trimming elements for tuning and matching can be upgraded to four trimming elements. Specifically, a second pair of variable capacitors can be installed, allowing for even broader frequency tuning range in the frequency-stepping experiments (typically beyond 20 MHz) or for double resonance experiments. Trimmer capacitors with a broad selection of capacitance ranges are available, both for room temperature and cryogenic applications.
Liquids, powders, and single-crystals holders made of various polymers (PMMA, Teflon, Vespel) or machinable ceramics (Macor) are available in various sizes (max. 10mm outer diameter).