NMR-MAS probe head with pivotable stator

Patent metadata

Field	Value
Publication number	US-10712410-B2
Application number	US-201916271032-A
Country	US
Kind code	B2
Filing date	Feb 8, 2019
Priority date	Feb 8, 2018
Publication date	Jul 14, 2020
Grant date	Jul 14, 2020

Abstract

A probe head ( 1 ) of an NMR-MAS assembly has a stator ( 2 ) with an opening ( 4 ) receiving a rotor ( 3 ) which, in a measuring position, rotates at the magic angle to the B 0 field. The stator is pivotable between the measuring position and a loading position of the rotor. A detection device ( 5 ) permits external, contactless identification of whether the opening of the stator is fitted with a rotor. The detection device has a light source ( 5 a ), from which light is introduced into a lower end ( 6 ″) of a light guide ( 6 ). The stator has a first bore ( 2 a ), in which a first light guide stump ( 7 a ) 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 ( 6 ′) of the light guide opposite the lower end.

First claim

What is claimed is:

1. A probe head of a Nuclear Magnetic Resonance (NMR) Magic Angle Spinning (MAS) assembly comprising:
a MAS stator having an opening configured to receive a MAS rotor in a loading position and to set the MAS rotor, which has a cylinder axis, in rotation in a measuring position in which the cylinder axis of the MAS rotor is at the magic angle to a B 0 field of the NMR-MAS assembly, wherein the MAS stator is arranged in the NMR-MAS probe head to pivot between the measuring position and the loading position,
a detection device configured to identify from outside the opening and without contacting the MAS rotor whether or not the opening of the MAS stator is fitted with the MAS rotor, and
a light guide having a lower end and an upper end opposite the lower end,

wherein the detection device comprises a light source configured to introduce light into the lower end of the light guide,
wherein the MAS stator has a first bore, in which a first light guide stump is positioned such that, in the loading position of the MAS stator, the first light guide stump produces an optical connection between the MAS rotor when inserted in the opening of the MAS stator and the upper end of the light guide.

2. The probe head as claimed in claim 1 , wherein the detection device has a light-sensitive detector arranged to detect light, from the lower end of the light guide, reflected by the MAS rotor when the MAS rotor is inserted in the opening of the MAS stator.

3. The probe head as claimed in claim 2 , further comprising an analysis unit configured to analyze signals of the light-sensitive detector and to determine whether or not the opening of the MAS stator is fitted with the MAS rotor.

4. The probe head as claimed in claim 1 , wherein the pivotable MAS stator is held mechanically to move from the measuring position into the loading position through a pivot angle γ≥3°.

5. The probe head as claimed in claim 4 , wherein the pivotable MAS stator is held to move from the measuring position into the loading position through a pivot angle γ>35°.

6. The probe head as claimed in claim 1 , wherein the MAS stator has a second bore, in which a second light guide stump is positioned such that, in the measuring position of the MAS stator, the second light guide stump produces an optical connection between an optical marking of the MAS rotor when the MAS rotor is inserted in the opening of the MAS stator and is rotating in the MAS stator and the upper end of the light guide when the optical marking of the MAS rotor, when rotating, moves past the upper end of the light guide.

7. The probe head as claimed in claim 6 , further comprising an analysis unit configured to analyze signals of the light-sensitive detector and to determine whether or not the opening of the MAS stator is fitted with the MAS rotor,
wherein the detection device has a light-sensitive detector arranged to detect light, from the lower end of the light guide, reflected by the MAS rotor when the MAS rotor is inserted in the opening of the MAS stator,
wherein the light-sensitive detector of the detection device is arranged to detect light reflected by the optical marking of the MAS rotor when the MAS rotor is inserted in the opening of the MAS stator and reaching the lower end of the light guide, and
wherein the analysis unit is configured to analyze the signals of the light-sensitive detector and, based on a periodic time dependency of the signals, to determine a rotation frequency of the MAS rotor when the MAS rotor is inserted in the opening of the MAS stator.

8. The probe head as claimed in claim 6 , wherein the first and the second light guide stumps have respective cylindrical shapes and respective cylinder axes oriented at an angle to one another that corresponds to a maximum pivot angle γ of the MAS stator from the measuring position into the loading position.

9. The probe head as claimed in claim 6 , wherein the first and the second light guide stumps have respective cylindrical shapes, wherein respective one ends of the light guide stumps facing the MAS rotor in the loaded operating state are ground flat at right angles to the respective cylinder axes, and wherein respective other ends of the light guide stumps facing the light guide are ground flat at an angle α obliquely to the respective cylinder axes.

10. The probe head as claimed in claim 9 , wherein the light guide stumps have respective refractive indices, and wherein the angle α is selected depending on the refractive indices of the light guide stumps.

11. The probe head as claimed in claim 10 , wherein the angle α is selected depending on the refractive indices of the light guide stumps and on a maximum pivot angle γ of the MAS stator from the measuring position into the loading position.

12. The probe head as claimed in claim 9 , wherein a production tolerance of the angle α is at most 5%.

13. The probe head as claimed in claim 9 , wherein in the loaded operating state of the MAS rotor, the cylinder axes of the two light guide stumps are arranged at differing respective angles to the cylinder axis of the MAS rotor in the opening of the MAS stator.

14. The probe head as claimed in claim 6 , wherein the light guide stumps are made of a material having a solid state in a temperature range between 100K and 470K and not exceeding a coefficient of thermal expansion of 2000*10 −6 /K.

15. The probe head as claimed in claim 14 , wherein the coefficient of thermal expansion does not exceed 100*10 −6 /K.

16. The probe head as claimed in claim 1 , wherein a center point of the MAS stator forms the axis of rotation for the pivoting of the MAS stator, and wherein a center point of the MAS rotor is arranged centrally in the B 0 field of the NMR-MAS assembly when the MAS rotor is inserted in the opening of the MAS stator.

17. The probe head as claimed in claim 1 , wherein the upper end of the light guide forms respective air gaps with the end, facing the light guide upper end, of the first light guide stump in the loading position of the MAS stator, and also with the end, facing the light guide upper end, of the second light guide stump in the measuring position of the MAS stator.

18. The probe head as claimed in claim 17 , wherein the respective air gaps have a size between 0.1 mm and 2 mm.

Assignees

• Bruker Biospin Gmbh

Inventors

• Krahn Alexander
• Osen David
• Purea Armin
• Mayer Markus
• Meister Roger

Classifications

• G01R33/307 Primary

  specially adapted for moving the sample relative to the MR system, e.g. spinning mechanisms, flow cells or means for positioning the sample inside a spectrometer · CPC title