The infrared spectra were obtained using a new supersonic jet gas recycling setup. The handling of the TEMPO radical (Sigma Aldrich, 98%) , was described elsewhere. TEMPO-H was synthesised according to a one-step procedure. . With the need for high purity solid samples of TEMPO-H, we modified a literature procedure as follows. Sodium ascorbate was reacted with TEMPO in deoxygenated water under vigorous stirring for 2 hrs. The resulting white precipitate was extracted with pentane and dried over anhydrous sodium sulfate. The pentane was removed in vacuo and sublimation of the white solid at -35 • C resulted in isolation of anhydrous white crystalline material in high purity and yield (91%). See the ESI † for details.