Nuclear quadrupole resonance thermometer

Electrical effects. Electrical methods are convenient because an electrical signal can be easily processed. Resistance thermometers (including thermistors) and thermocouples are the most widely used. Other electrical methods include noise thermometers using the Johnson noise as a temperature indicator resonant-frequency thermometers, which rely on the temperature dependence of the resonant frequency of a medium, including nuclear quadrupole resonance thermometers, ultrasonic thermometers, and quartz thermometers and semiconductor-diode thermometers, where the relation between temperature and junction voltage at constant current is used. 

In a resonant-frequency thermometer, the resonance frequency of the medium serves as the temperature indicator. Included in this category are nuclear quadrupole resonance thermometers, quartz thermometers, and ultrasonic thermometers. These thermometers usually... 

Nuclear quadrupole resonance thermometers [83] can be used between 20 and 400 K. In the ultralow temperature range below 1 K, a direct measurement of temperature is feasible by using the spectrometer to measure the intensity ratio of magnetic resonance lines [84]. A precision and accuracy of 1 mK can be achieved. However, these thermometers are quite expensive and are therefore used most often as transfer standards... 

Yokagawa Electric Works has developed a thermometer based on the nuclear quadrupole resonance of potassium chlorate, usable over the range from —184 to 125°C. This thermometer makes use of the fundamental properties of the absorption frequency of the 35C1 nucleus, and its calibration is itself a constant of nature. 

A. Ohte and H. Iwaoka, A New Nuclear Quadrupole Resonance Standard Thermometer, in Temperature Its Measurement and Control in Science and Industry, vol. 5, pt. 2, pp. 1173-1180, American Institute of Physics, New York, 1982. 

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