Home built 95 GHz pulse EPR spectrometer

The spectrometer features electron – electron and electron nuclear double resonance capabilities (DEER and ENDOR). It employs a superconducting magnet with a solenoid-coil configuration that can reach a maximum field of 6T . The warm bore of 90 mm diameter is equipped with a superconducting sweep coil with permanent current leads to produce a sweep range of ±0.3 T. The magnet is fitted with a variable temperature insert with a temperature range from 2.5 to 300 K using liquid or gaseous helium for cooling. The probehead set-up is based on a cylindrical TE011 cavity, with an rf Helmholtz coil a round the cavity. In addition, there is a mechanism that allows for the rotation of the sample holder around the cavity axis for single-crystal measurements. Typical sample sizes are 0.8 mm o.d. tubes with a length of about 10 mm, out of which ~2 mm are in the active area of the cavity. A detailed description of the probehead in given in Reference 1, The MW bridge described in this reference has been replaced with a new bridge.

The new bridge features two pulse channels and a coherent heterodyne receiver. The two channels have independent frequency/power/phase controls. For the two channels π/2 pulse of 12-16 µs are easily achieved with a cavity with a Q~1000. Typical rf π pulses for protons (~144 MHz) are in the range of 15 -25 µs, whereas for deuterons it is ~ 40 µs.

The flexibility required for running multi-dimensional experiments and for implementing different acquisition modes is highly demanding in terms of the software that manages the spectrometer. Our spectrometer is controlled using SpecMan.

References

W-Band spectrometer