Method for Two Field Nuclear Magnetic Resonance Measurements

Patent metadata

Field	Value
Publication number	US-2016299204-A1
Application number	US-201615096287-A
Country	US
Kind code	A1
Filing date	Apr 12, 2016
Priority date	Apr 13, 2015
Publication date	Oct 13, 2016
Grant date	—

Abstract

A method for carrying out two-field nuclear magnetic resonance (=2FNMR) measurements involves preparing a sample ( 9 a ) in a first working volume ( 5 ) of a highly homogeneous magnetic field with a first field strength; transferring the sample ( 9 a ) to a second working volume ( 7 ) with a magnetic field having lower homogeneity and having a second field strength, wherein the first field strength is at least 2 Tesla larger than the second field strength; manipulating the sample ( 9 a ) at the second working volume ( 7 ) by applying a sequence of radio-frequency (=RF) and/or field gradient pulses; transferring the sample ( 9 a ) back to the first working volume ( 5 ); and detecting an NMR signal of the sample ( 9 a ) in the first working volume ( 5 ). The method allows for NMR experiments with which more and/or improved quality information about an investigated sample can be obtained.

First claim

We claim:

1 . A method for carrying out two-field nuclear magnetic resonance (=2FNMR) measurements on a sample, the method comprising the steps of:
a) preparing the sample during a preparation period in a first working volume of a first magnetic field with a first field strength and having a homogeneity better than 0.01 ppm; b) transferring, during a first transfer period, the sample to a second working volume with a second magnetic field having a homogeneity of 100 ppm or better or in a range between 2 ppm and 100 ppm, and having a second field strength of 0.05 Tesla or larger or of 0.1 Tesla or larger, wherein the first field strength is at least 2 Tesla larger than the second field strength; c) manipulating, during a manipulation period, the sample at the second working volume by applying a sequence of radio-frequency (=RF) and/or field gradient pulses, wherein the sequence is insensitive to or minimizes effects of an inhomogeneity of the second magnetic field in the second working volume; d) transferring the sample back to the first working volume during a second transfer period; and e) detecting an NMR signal of the sample in the first working volume.

2 . The method of claim 1 , wherein in step c), the RF and/or field gradient pulse sequence is insensitive to or minimizes the effects of the inhomogeneity of the magnetic field in the second working volume by exciting and/or filtering nuclear spin transitions with energy differences independent of local variations of a strength of the magnetic field in the second working volume.

3 . The method of claim 1 , wherein in step c), the RF and/or field gradient pulse sequence excites zero- or multiple-quantum coherences of nuclear spins of the sample in the second working volume.

4 . The method of claim 1 , wherein the steps a) through e) are repeated with the sample several times, for obtaining a multidimensional NMR measurement which displays at least one dimension based on a development and/or manipulation of nuclear spins of the sample in the second working volume and at least one dimension based on a development and/or manipulation of nuclear spins of the sample in the first working volume.

5 . The method of claim 4 , wherein, in each step c), at least one time parameter of the sequence of RF and/or field gradient pulses is set to a different value.

6 . The method of claim 1 , wherein the 2FNMR measurement includes a two-field zero-quantum NMR spectroscopy experiment, with building-up and preparing polarization of nuclei of a specific type during step a), with a sequence of RF pulses, delays and field gradient pulses generating and filtering zero-quantum coherences of a specific type during step c), and with detecting single-quantum coherences during step e).

7 . The method of claim 6 , wherein the nuclei of a specific type comprises 13C nuclei.

8 . The method of claim 1 , wherein a total duration of the first and second transfer periods and the manipulation period is less than a spin-lattice relaxation time of nuclear spins of the sample manipulated in the second working volume during step c).

9 . The method of claim 1 , wherein the first and the second transfer period each have a duration of less than 100 ms.

10 . The method of claim 1 , wherein a sequence of RF and/or field gradient pulses is applied to the sample in the first working volume during step a).

11 . The method of claim 1 , wherein step e) includes applying a single or a sequence of RF and/or field gradient pulses to the sample in the first working volume before starting NMR signal acquisition.

12 . The method of claim 1 , wherein step c) is triggered by position sensors sensing a position of the sample in the second working volume and/or that step e) is triggered by position sensors sensing a position of the sample in the first working volume.

13 . The method of claim 1 , wherein NMR probes at the first and second working volume are synchronized.

14 . The method of claim 1 , wherein the preparation period of step a) is longer than a spin relaxation time in the first working volume of the nuclear spins of the sample manipulated during step c).

15 . The method of claim 1 , wherein, during step a) and/or step c) and/or step e), RF and/or field gradient pulses are applied to different types of nuclei of the sample.

16 . The method of claim 15 , wherein nuclear spins of the different nuclei are manipulated at different working volumes.

17 . The method of claim 1 , wherein, during step a) and/or step c) and/or step e), RF and/or field gradient pulses are applied only to nuclei of the sample which have an electric quadrupole moment of zero.

18 . The method of claim 17 , wherein the nuclei of the sample are 1 H, 13C and/or 15N.

19 . The method of claim 1 , wherein during step c), a pulse sequence performs a transfer of polarization in networks of nuclei through scalar coupling interactions or a transfer of polarization by isotropic mixing.

Assignees

• Bruker S A S
• Ecole normale supérieur
• Centre Nat Rech Scient
• Univ Pierre Et Marie Curie Paris 6

Inventors

• Cousin Samuel
• Charlier Cyril
• Ferrage Fabien
• Tyburn Jean-Max
• Marquardsen Thorsten

Classifications

• G01R33/4616 Primary

  using specific RF pulses or specific modulation schemes, e.g. stochastic excitation, adiabatic RF pulses, composite pulses, binomial pulses, Shinnar-le-Roux pulses, spectrally selective pulses not being used for spatial selection · CPC title

• G01R33/387

  Compensation of inhomogeneities · CPC title

• G01R33/445

  MR involving a non-standard magnetic field B0, e.g. of low magnitude as in the earth's magnetic field or in nanoTesla spectroscopy, comprising a polarizing magnetic field for pre-polarisation, B0 with a temporal variation of its magnitude or direction such as field cycling of B0 or rotation of the direction of B0, or spatially inhomogeneous B0 like in fringe-field MR or in stray-field imaging · CPC title

• G01R33/3635

  Multi-frequency operation · CPC title

• G01R33/307

  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