Cryogenic 35GHz pulse ENDOR probehead accommodating large sample sizes: Performance and applications

• DOI: 10.1016/j.jmr.2009.06.007
• Publication Date: 2009-06-13T05:04:59Z
• Authors: René Tschaggelar; Besnik Kasumaj; Maria Grazia Sant...; Jörg Forrer; Patrik Leger; Henry Dube; François Diederich; Jeffrey Harmer; Rolf Schuhmann; Inés García-Rubio; Gunnar Jeschke
• Keywords: Large sample resonator; Indoles; Porphyrins; Electron Spin Resonance Spectroscopy; Glycine; Pulse EPR; Isoindoles; Helium; 01 natural sciences; 7. Clean energy; 0104 chemical sciences; Cold Temperature; Coal; Electromagnetic Fields; ENDOR resonator; Q-band probehead; Metalloproteins; Organometallic Compounds; Computer Simulation; ENDOR; Pulse EPR; ENDOR resonator; Q-band probehead; Large sample resonator; Endor; Algorithms

The construction and performance of a cryogenic 35GHz pulse electron nuclear double resonance (ENDOR) probehead for large samples is presented. The resonator is based on a rectangular TE(102) cavity in which the radio frequency (rf) B(2)-field is generated by a two turn saddle ENDOR coil crossing the resonator along the sample axis with minimal distance to the sample tube. An rf power efficiency factor is used to define the B(2)-field strength per square-root of the transmitted rf power over the frequency range 2-180MHz. The distributions of the microwave B(1)- and E(1)-field, and the rf B(2)-field are investigated by electromagnetic field calculations. All dielectrics, the sample tube, and coupling elements are included in the calculations. The application range of the probehead and the advantages of using large sample sizes are demonstrated and discussed on a number of paramagnetic samples containing transition metal ions.