MEASUREMENT OF TEMPERATURE IN C-13 CP MAS NMR

A method for temperature calibration of CP/MAS NMR probes and their te mperature controllers is described that relies upon known phase change s in the compounds adamantane, d-camphor, pivalic acid and DABCO. The method appears to give a convenient and reliable calibration over the temperature range ca. 173-373 K. In a separate experiment, making use of a well defined lineshape coalescence, it was shown that the tempera ture effect of spinning in a 4 mm Bruker MAS probe with zirconia rotor s could be fitted by a squared relationship but that if treated as app roximately linear the variation was ca. 1 K kHz(-1)