A DNP SPECTROMETER AT 1.94 T MAGNETIC FIELD

We describe a home-made dynamic nuclear polarizatioD （DNP） spectrometer at a fieldof 1.94 T, corresponding to Larmor frequencies 83 MHz and 54 GHz for proton and electron,respectively. Its NMR part is a modified Bruker WP--80SY spectrometer. A 6--mm EIO （ex-tended interaction oscillator） Klystron D3070, with a maximum output power of 30W in cwmode, served as the microwave source of ESR. In 1H and 13C DNP and DNP--CP （crosspolarization） experiments the probe consisted of a horn-antenna, a movable reflector and adouble-tuned circuit for 1H and 13C. The proton and carbon NMR signals were enhanced byone to two orders of magnitude for typical samples. Some results are presented in thispaper.