US4345207A
Expired / Lapsed
US
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Method and apparatus for obtaining enhanced NMR signals
Assignee: United States Department of the Navy
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Filing: 1980-04-24
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Granted: 1982-08-17
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Expires: 2000-04-24
Abstract
Abstract A method and device of NMR spectroscopic analysis of liquids whereby magnzation of the spins of one nuclear species in spin-locked along a certain direction and the spin polarization of this species is transferred to a second species through the modulation of the amplitude and/or phase of rf fields applied to one or both species. The NMR signal can be detected directly from the second species.
Inventors
- 👤 Richard D. Bertrand
- 👤 Gerard C. Chingas
- 👤 Allen N. Garroway
- 👤 William B. Moniz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 17:07
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/20; G01R33/44; G01R33/46; G01R33/28; G01R33/32; G01R33/36; G01R33/3607
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
106 words
A method for NMR spectroscopic analysis of liquids having at least two nuclear spin species which comprises: subjecting said liquid to a magnetic field; transferring pin polarization from at least one nuclear species to at least one other nuclear species by the steps comprising: spin-locking at least one species by rf irradiation; modulating the amplitude and/or phase of said spin locking rf irradiation; and applying other rf irradiation that varies in amplitude and/or phase to at least one other nuclear species so that spin polarization is transferred from said spin-locked nuclear species to said other species; and detecting directly the NMR signal from said other species.
Claim 2
Independent Claim
106 words
A method for NMR spectroscopic analysis of liquids having at least two nuclear spin species which comprises: subjecting said liquid to a magnetic field; transferring pin polarization from at least one nuclear species to at least one other nuclear species by the steps comprising: spin-locking at least one species by rf irradiation; modulating the amplitude and/or phase of said spin locking rf irradiation; and applying other rf irradiation that varies in amplitude and/or phase to at least one other nuclear species so that spin polarization is transferred from said spin-locked nuclear species to said other species; and detecting directly the NMR signal from said other species.
Claim 3
Dependent Claim
19 words
The method of claim 1 wherein said spin polarization is transferred to two or more nuclear species in sequence.
Claim 4
Dependent Claim
33 words
The method of claim 1 wherein spin polarization is transferred from a species with a higher magnetogyric ratio to one with a lower ratio thereby enhancing the signal strength of the second species.
Claim 5
Dependent Claim
98 words
The method of claim 1 wherein spin polarization is transferred by the steps comprising: spin-locking one nuclear species by rf irradiation; applying rf irradiation to a second species; setting the total time for said polarization transfer to be about 4/J; removing, for a duration of about t 90 , rf irradiation from either said nuclear species at a time about one fourth of the way into the polarization transfer; and removing, for a duration of about t 90 , rf irradiation from said other nuclear species at a time which is about three fourths into the polarization transfer.
Claim 6
Dependent Claim
37 words
The method of claim 1 in which the step of transferring spin polarization further comprises: applying an extension pulse to the rf irradiation to either spin species while turning off the rf irradiation to the spin species.
Claim 7
Dependent Claim
29 words
The method of claim 5 wherein said extension pulse is applied 90° out of phase with the rf irradiation to the species to which said extension pulse is applied.
Claim 8
Independent Claim
20 words
The method of claims 5 or 6 wherein extension pulse is applied for a duration of about t 90 .
Claim 9
Dependent Claim
12 words
The method of claim 1 wherein said spin polarization is transferred adiabatically.
Claim 10
Dependent Claim
108 words
The method of claim 8 wherein said spin polarization is adiabatically transferred by the steps comprising: spin-locking at least one species by rf irradiation with an amplitude such that the nutation rate is at least 2 times greater than J; decreasing slowly the amplitude of said spin-locking rf irradiation; simultaneously applying rf irradiation with an amplitude initially smaller than the amplitude of said spin-locking rf irradiation to another species; increasing slowly the amplitude of said irradiation to said other species until the amplitude of said irradiation is at least 2J greater than the instantaneous amplitude of said spin-locking rf irradiation; removing said rf irradiation to said other species.
Claim 11
Dependent Claim
24 words
The method of claim 9 wherein the amplitude of said rf irradiation to either species is changed by an amount greater than about 2J.
Claim 12
Dependent Claim
24 words
The method of claim 9 wherein the amplitude of said rf irradiation to each species is changed by an amount greater than about 2J.
Claim 13
Dependent Claim
30 words
The method of claim 9 wherein the changes in one of the of the rf irradiation amplitude is about 2J and the duration is about 5 times longer than 1/J.
Claim 14
Dependent Claim
14 words
The method of claim 9 wherein said irradiation to said other species is constant.
Claim 15
Dependent Claim
71 words
The method of claim 8 wherein said spin polarization is transferred adiabatically by the steps comprising: spin-locking at least one nuclear species by rf irradiation; reducing the amplitude of said spin locking rf irradiation to zero; applying other rf irradiation to at least one other nuclear species after the amplitude of said spin locking rf irradiation becomes zero; and increasing the amplitude of said other rf irradiation to at least 2J.
Claim 16
Dependent Claim
46 words
The method of claim 8 wherein said spin polarization is transferred adiabatically by the steps comprising: spin-locking at least one nuclear species by rf irradiation; reducing the amplitude of said spin locking rf irradiation to zero; and applying a π/2 rf pulse to one nuclear species.
Claim 17
Dependent Claim
34 words
In a two-channel spectrometer wherein two rf carriers are generated and applied to nuclear species in a liquid sample, the combination, with each channel, which comprises means for modulating the amplitude of each carrier.
Claim 18
Dependent Claim
34 words
In a two-channel spectrometer wherein two rf carriers are generated and applied to nuclear species in a liquid sample, the combination, with each channel, which comprises means for modulating the amplitude of each carrier.
Claim 19
Dependent Claim
34 words
The spectrometer of claim 16 wherein said modulating means comprises: a programmed computer; and means for converting digital pulses received from said computer into dual channel voltage ramps of settable slope and dc level.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-08-16 | 1986-02-15 | 1986-08-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-08-16 | 1990-02-15 | 1990-08-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-08-16 | 1994-02-15 | 1994-08-17 | $7700.00 | Window Closed / Lapsed |