Cold probe (NMR)
In NMR spectroscopy a cold probe, also referred to as a Cryoprobe® (Bruker, Inc.) or a Chiliprobe® (Varian, Inc.), is a radio frequency (typically 600-900 MHz) exitation and receiving probe in which the electronics are cooled to about 15-25 degrees above absolute zero. By doing this the electronic noise normally associated with electronic circuits is greatly reduced, resulting in a large signal-to-noise ratio (S/N) improvement. This allows data collection in about 1/10th of the time normally required using a room temperature probe for a similar S/N ratio.
Cold probes are placed under a vacuum, with pressures in the range of 10-5 to 10-8 Torr. Cooling is achieved with the use of a helium compressor, often supported by a secondary cooling devise to help remove the heat generated by the helium pump. The secondary cooling devise is generally a circulating water cooler.