Bruker Biospin Gmbh

Armin Purea

David Osen

Alexander Krahn

Benno Knott

Nicolas Freytag

Roger Meister

Markus Mayer

Frank Engelke

Alia Hassan

Fabian Kuehler

Jevgeni Guidoulianov

Florian Helbing

Christian Reiter

Alexandros I Dimitriadis

Arndt Von Bieren

I Alexandros Dimitriadis

Fabian Kühler

A probe head () of an NMR-MAS assembly has a stator () with an opening () receiving a rotor () which, in a measuring position, rotates at the magic angle to the Bfield. The stator is pivotable between the measuring position and a loading position of the rotor. A detection device () permits external, contactless identification of whether the opening of the stator is fitted with a rotor. The detection device has a light source (), from which light is introduced into a lower end (&#x2033;) of a light guide (). The stator has a first bore (), in which a first light guide stump () is positioned such that, in the loading position of the stator, it produces an optical connection between a rotor inserted in the stator and an upper end (') of the light guide opposite the lower end.

NMR-MAS probe head with pivotable stator

An NMR-MAS probehead having an MAS stator () receiving an MAS rotor () that is surrounded by an RF coil () and that has a sample substance, and having a first microwave guide () supplying microwave radiation into a sample volume () through a coil block (). The coil block is constructed from dielectric material, is inserted into the wall of the MAS stator so that it surrounds the RF coil and the MAS rotor, and has a first bore (') that extends coaxially with the longitudinal axis of the elongate MAS rotor, the RF coil being fastened to the inner wall of said first bore, as well as a second bore (&#x2032;) that extends coaxially with the longitudinal axis of the first microwave guide and has a hollow, elongate second microwave guide () supplying microwave radiation from the first microwave guide into the sample volume.

NMR-MAS probehead with an optimized MAS-DNP coil block for fast sample rotation

A method for operating an NMR probehead () with an MAS stator () receiving a circular-cylindrical hollow MAS rotor () with an outer jacket. The MAS rotor is mounted on pressurized gas in a measuring position within the MAS stator via a gas supply device with a bearing nozzle (') and rotates about the cylinder axis of the MAS rotor at a rotation frequency f&#x2265;30 kHz. During a measurement, a temperature control gas is blown by a temperature control nozzle () onto the outer jacket of the rotor at an angle &#x3b1;&#x3c;90&#xb0; with respect to the longitudinal axis of the cylinder-symmetrical rotor. The flow speed of the temperature control gas corresponds in the nozzle cross section to at least half the circumferential speed of the outer jacket of the rotating rotor and to at most the speed of sound in the temperature control gas.

Temperature control of an NMR-MAS rotor

An NMR probe head with an MAS stator () supplied with microwave radiation from a microwave guide () through an opening in a coil block () has a microwave lens () and a microwave mirror () on an inner side of the MAS stator. The MAS rotor () is surrounded by a solenoid RF coil () and the microwave lens is arranged and embodied in the opening of the coil block on the side facing a sample volume () such that the cylinder axis of the MAS rotor lies in the focus of the microwave lens. The microwave mirror is arranged on, or in, the inner wall of the MAS stator that lies opposite the microwave guide and has a cylindrical and concave structure, such that the microwave mirror focuses the microwave radiation incident from the sample volume onto the central axis of the MAS rotor.

Mas stator of an NMR probe head with optimized microwave irradiation

An MAS stator () for an NMR-MAS probe head () has a bottom bearing () with at least one nozzle and at least one radial bearing (), wherein one substantially circular cylindrical MAS rotor () is provided for receiving a measurement substance. The MAS rotor can be supported by compressed gas in a measurement position within the MAS stator by means of a gas supply device and can be rotated about the cylinder axis of the MAS rotor by means of a pneumatic drive. A suction device () is provided in a space below the radial bearing for suctioning-off the gas introduced by the gas supply device, and generates an underpressure in the space below the radial bearing during measurement operation. This provides a stator for NMR-MAS spectroscopy in which the closure at the head end of the stator is omitted.

MAS-stator with suctioning-off device

An NMR DNP-MAS probe head () has an MAS stator () for receiving an MAS rotor () having a sample substance in a sample volume (), and a hollow microwave waveguide ()' for feeding microwave radiation through an opening () of the microwave waveguide into the sample volume, an axially expanded rod-shaped microwave coupler () located in the opening made of dielectric material, characterized in that the microwave waveguide has a conically tapered hollow transition piece for coupling in an HE 11 mode, into which the microwave coupler projects at an all-round radial distance to the opening of the microwave waveguide. It is thus possible, in a surprisingly simple manner and by means of readily available technical means, to irradiate a considerably higher microwave energy in the HE 11 mode into the NMR measuring sample than by means of the known arrangements.

Microwave coupler for optimizing a NMR probe head for MAS-DNP

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Bad Schoenborn, Germany

Armin Purea