TY  - JOUR
AU  - Tol, J. van
AU  - Brunel, L-C
AU  - Wylde, R. J.
PY  - 2005
DA  - 2005//
TI  - A quasioptical transient electron spin resonance spectrometer operating at 120 and 240 GHz
T2  - Rev. Sci. Instrum.
JO  - Rev. Sci. Instrum.
SP  - 074101 (1 to 8)
VL  - 76
IS  - 7
KW  - Schottky
KW  - noise temperature
AB  - A new multifrequency quasioptical electron paramagnetic resonance (EPR) spectrometer is described. The superheterodyne design with Schottky diode mixer/detectors enables fast detection with subnanosecond time resolution. Optical access makes it suitable for transient EPR (TR-EPR) at 120 and 240 GHz. These high frequencies allow for an accurate determination of small g-tensor anisotropies as are encountered in excited triplet states of organic molecules like porphyrins and fullerenes. The measured concentration sensitivity for continuous-wave (cw) EPR at 240 GHz and at room temperature without cavity is 1013  spins/cm3 (15 nM) for a 1 mT linewidth and a 1 Hz bandwidth. With a Fabry-Perot cavity and a sample volume of 30 nl, the sensitivity at 240 GHz corresponds to [approximate]3×109 spins for a 1 mT linewidth. The spectrometer's performance is illustrated with applications of transient EPR of excited triplet states of organic molecules, as well as cw EPR of nitroxide reference systems and a thin film of a colossal magnetoresistance material.
N1  - Actually, noise spectral density is given (3e-19 W/Hz)
ID  - Tol_etal2005
ER  -