Bruker Biospin Gmbh

Other

Ion Prisecaru

Peter Hoefer

Lukas Haenichen

Peter Höfer

An electron paramagnetic resonance (EPR) spectrometer includes a magnet system comprising at least one magnet and at least one pole piece for producing a magnetic field along a pole axis in a field of view in front of the at least one pole piece. A probe head comprising a microwave resonator and at least one modulation coil or rapid scan coil produces an additional, time-varying magnetic field aligned along the pole axis. The probe head is arranged in the field of view, and a respective modulation coil or rapid scan coil is arranged between the microwave resonator and a respective pole piece. For each pole piece, at least a part of said pole piece is made of a function material having an electric conductivity σof 10S/m or less, and having a saturation magnetic flux density BSof 0.2 T or more.

EPR spectrometer with at least one pole piece made at least partially of a function material

A coupling device is provided for coupling microwave radiation from a first microwave structure, in particular a microwave waveguide, into a second microwave structure, in particular a microwave resonant cavity, wherein the first and second microwave structures share a common wall, through an iris opening in said wall in front of which the coupling device is positioned on the side of the first microwave structure, in particular wherein the coupling device is of a basically cylindrical shape, characterized in that the coupling device comprises N electrically conducting conductor loops, with N≥3, preferably 3≤N≤20, that the conductor loops are arranged coaxially in an array along a z-axis, and that axially neighboring conductor loops are separated by a dielectric. The inventive coupling device allows for a larger coupling coefficient, and in particular allows for a larger dynamic range.

Microwave coupling device for iris apertures, comprising a plurality of conductor loops

A microwave resonator for an electron paramagnetic resonance probehead comprises a cavity body supporting an electromagnetic microwave resonance mode, at least one sample opening for inserting a sample in a sample container, at least one microwave opening for transmitting microwave radiation into the resonator, and at least one access opening for inserting and removing a modifier in a modifier vessel into or out of the cavity body. The modifier vessel is fixed in the at least one access opening, the modifier is a fluid comprising attenuator fluid and/or marker fluid and/or adaptor fluid, and the modifier vessel has an insert opening for filling and discharging the modifier gradually into or out of the cavity body. This improves performance greatly, enabling a gradual modification of specific experimental conditions without moving any mechanical parts in the cavity body, and without changing other experimental conditions for Q- and/or M- and/or D-variation.

Microwave resonator for an EPR probehead providing Q-, M- and D-variation using a variable fluid volume

An EPR resonator for a cylindrical TE01n microwave mode, where n=1, 2, 3, or 4, has: a cylindrical body () which has an RF absorption of less than 5% at RFs below 1 kHz, a first plunger () delimiting the resonating volume within the body in an axial direction at a first end and a second plunger () delimiting the resonating volume within the body at a second end, the second plunger having an opening () for inserting an EPR sample. The first and second plunger each has a spiral winding of an electrically conductive filament wherein neither the ends nor neighboring turns of the spiral windings have electrically conductive connections prone to forming electrically closed loops. Using spiral winding plungers for cylindrical TE01n microwave modes provides equivalent functionality compared to conventional plungers, but without creating Eddy currents at frequencies lower than the frequency of the TE01n microwave mode.

EPR resonator with extended transparency and homogeneity in RF range

A microwave resonator for an EPR probe head has a metal cavity body () supporting an electromagnetic microwave resonance mode. The metal cavity body () has an opening for inserting a sample tube () to a center position of the resonator. The center of the opening and the center position of the resonator define an x-axis. The cavity body also has an opening for transmitting microwave radiation into the resonator. Two dielectric elements () are located symmetrically to the E-field nodal plane containing the x-axis and a z-axis perpendicular to the x-axis. Each dielectric element is geometrically formed and positioned such that it provides an equal overlap with a local maximum of the microwave electric field energy. The microwave resonant cavity has a thin planar shape and the resonator is loaded with two dielectric elements, placed symmetrically relative to the central EPR sample.

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Karlsruhe, Germany

Ion Prisecaru