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The homebuilt S-Band Spectrometer

Since 1998, a spectrometer has been developed whose operating frequency can be set between 2.7 and 3.7 GHz, corresponding to magnetic fields of 900 to 1300 G. This spectrometer is used for pulsed EPR (although cw experiments are 'feasible' too.) The probe head (Bruker FlexLine) is located inside an Oxford Instruments CF935 cryostate, whose temperature can be controlled between 4 K and room temperature.
Different bridge-loop-gap cavities [1] are used: homebuild once and Bruker's 'S-Band Split Ring Resonator'.
Most devices are connected via a Bruker EleXsys console to the Bruker Xepr software for controlling. The spectrometer design also includes PELDOR. A block diagram of the setup shows some more details. You can download a poster with further informations about the S-Band spectrometer and its applications.

On the left you can see a typical application of the S-Band spectrometer. This is a 3 pulse ESEEM on a tyrosine radical in photosystem II. The deep ESEEM modulation is due to the low frequency!


[1] S. Pfenniger, J. Forrer, A. Schweiger, Rev. Sci. Instrum. 59 (5), 752 - 760 (1988)

For technical questions ask Burkhard Endeward.