ELECTRON-SPIN-ECHO SPECTROSCOPY AT 604-GHZ USING FIR LASERS

We demonstrate that electron-spin-echo spectroscopy is possible at 604 GHz, corresponding to a magnetic field of 21.6 T for a g-factor of tw o. The problems concerning suitable microwave equipment for EPR at ver y high frequencies are circumvented by the use of optical techniques. For the generation of the high frequency radiation, two pulsed, optica lly pumped FIR lasers are used. The detector consists of a Schottky-di ode in a heterodyne detection scheme with a cw FIR laser as local osci llator. A sensitivity of 10(12) spins per gauss is achieved.