US3792346A
Expired / Lapsed
US
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Proton-enhanced nuclear induction spectroscopy
Assignee: Massachusetts Institute of Technology
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Filing: 1972-11-20
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Granted: 1974-02-12
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Expires: 1992-11-20
Abstract
Abstract A method is described for the detection of the natural magnetic and/or electric quadrupole reasonance frequencies of isotopically rare or chemically dilute nuclei in the presence of at least one abundant nuclear spin species. The free induction decay of the dilute nuclei is directly detected after an applied r.f. field at the Larmor frequency of the dilute nuclei is removed. A high resolution spectrum of the dilute nuclei is obtained by applying an r.f. field at the Larmor frequency of the abundant spin system during the detection interval.
Inventors
- 👤 M Gibby
- 👤 A Pines
- 👤 J Waugh
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 23:01
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/20; G01R33/44; G01R33/46; G01R33/4608; G01R33/62
Claims Analysis
Total Claims: 36
Claim 1
Independent Claim
100 words
A method for improving the signal-to-noise ratio and resolution of the NMR spectrum of a dilute nuclear spin system, the S-spins, in a solid in the presence of a more concentrated nuclear spin system, the I-spins comprising the steps of 1. transfering nuclear polarization from the I-spins to the Sspins and, 2. then applying radiofrequency fields in the neighborhood of the I-spin Larmor frequency to reduce the broadening of the Sspin resonance which would otherwise be caused by said I-spins, and 3. detecting the nuclear induction radiation signal of the Sspins obtained from the S-spin polarization acquired via the Ispins.
Claim 2
Independent Claim
100 words
A method for improving the signal-to-noise ratio and resolution of the NMR spectrum of a dilute nuclear spin system, the S-spins, in a solid in the presence of a more concentrated nuclear spin system, the I-spins comprising the steps of 1. transfering nuclear polarization from the I-spins to the Sspins and, 2. then applying radiofrequency fields in the neighborhood of the I-spin Larmor frequency to reduce the broadening of the Sspin resonance which would otherwise be caused by said I-spins, and 3. detecting the nuclear induction radiation signal of the Sspins obtained from the S-spin polarization acquired via the Ispins.
Claim 3
Dependent Claim
29 words
then applying radiofrequency fields in the neighborhood of the I-spin Larmor frequency to reduce the broadening of the S-spin resonance which would otherwise be caused by said I-spins, and
Claim 4
Dependent Claim
29 words
then applying radiofrequency fields in the neighborhood of the I-spin Larmor frequency to reduce the broadening of the S-spin resonance which would otherwise be caused by said I-spins, and
Claim 5
Dependent Claim
63 words
The method of claim 1 in which step 1 is accomplished by an adaptation of rotating frame, double-resonance procedures, comprising polarizing said sample ofI-spins of I-spins spin-lattice processes, cooling the I-spins in their rotating frame, establishing contact between I and S spin system by turning on an r.f. field, H1(S), near the Larmor frequency of S-spins, thereby acquiring said S-spin polarization along H1(S).
Claim 6
Dependent Claim
18 words
detecting the nuclear induction radiation signal of the S-spins obtained from the S-spin polarization acquired via the I-spins.
Claim 7
Dependent Claim
18 words
detecting the nuclear induction radiation signal of the S-spins obtained from the S-spin polarization acquired via the I-spins.
Claim 8
Dependent Claim
53 words
The method of claim 1 in which step 1 is accomplished by ''''solid effect'''' techNiques, comprising polarizing said system of I-spins by spin-lattice processes, irradiating the sample with an r.f. field at the sum or difference of the I-spins and S-spins Larmor frequencies, thereby acquiring said S-spins polarization along the laboratory Zeeman field.
Claim 9
Dependent Claim
89 words
The method of claim 1 in which step 1 is accomplished by a rotating frame version of the ''''solid effect'''' technique, comprising polarizing said sample I-spins by spin-lattice processes, cooling the I-spins in their rotating frame by spin-locking said I-spins along an r.f. field, H1(I), simultaneously applying an r.f. field, H1(S), to the S-spins and an audio frequency magnetic field parallel to the laboratory Zeeman field direction with a frequency of gamma IH1(I) + gamma sH1(S) or gamma IH1(I) - gamma sH1(S), thereby acquiring said S-spins polarization along H1(S).
Claim 10
Dependent Claim
67 words
The method of claim 1 in which step 1 is accomplished by mixing the I and S spin systems in weak magnetic fields, comprising polarizing said sample of I-spins by spin-lattice processes in a large laboratory magnetic field, removing the sample to a weak magnetic field thereby enabling I-S mixing, returning the sample to the large magnetic field thereby acquiring S-spins polarization along the laboratory Zeeman field.
Claim 11
Dependent Claim
23 words
The method of claim 1 in which step 2 is accomplished by continuous wave irradiation of the sample near the I-spin Larmor frequency.
Claim 12
Dependent Claim
42 words
The method of claim 1 in which step 2 is accomplished by pulsed irradiation near the I-spin Larmor frequency comprising a train of 180* pulses spaced in time of the order of the shorter of the I-spin or S-spin spin-spin relaxation times.
Claim 13
Dependent Claim
48 words
The method of claim 1 comprising, in addition, acquiring said S-spin polarization a plurality of times, detecting said S-spins free induction decay after each polarization to provide a plurality of signals, averaging the S-spin signals to provide an averaged S-spin nuclear induction signal from a single I-spin polarization.
Claim 14
Dependent Claim
48 words
The method of claim 2 comprising, in addition, acquiring said S-spin polarization a plurality of times, detecting said S-spins free induction decay after each polarization to provide a plurality of signals, averaging the S-spin signals to provide an averaged S-spin nuclear induction signal from a single I-spin polarization.
Claim 15
Dependent Claim
48 words
The method of claim 3 comprising, in addition, acquiring said S-spin polarization a plurality of times, detecting said S-spins free induction decay after each polarization to provide a plurality of signals, averaging the S-spin signals to provide an averaged S-spin nuclear induction signal from a single I-spin polarization.
Claim 16
Dependent Claim
48 words
The method of claim 4 comprising, in addition, acquiring said S-spin polarization a plurality of times, detecting said S-spins free induction decay after each polarization to provide a plurality of signals, averaging the S-spin signals to provide an averaged S-spin nuclear induction signal from a single I-spin polarization.
Claim 17
Dependent Claim
48 words
The method of claim 5 comprising, in addition, acquiring said S-spin polarization a plurality of times, detecting said S-spins free induction decay after each polarization to provide a plurality of signals, averaging the S-spin signals to provide an averaged S-spin nuclear induction signal from a single I-spin polarization.
Claim 18
Dependent Claim
48 words
The method of claim 6 comprising, in addition, acquiring said S-spin polarization a plurality of times, detecting said S-spins free induction decay after each polarization to provide a plurality of signals, averaging the S-spin signals to provide an averaged S-spin nuclear induction signal from a single I-spin polarization.
Claim 19
Dependent Claim
48 words
The method of claim 7 comprising, In addition, acquiring said S-spin polarization a plurality of times, detecting said S-spins free induction decay after each polarization to provide a plurality of signals, averaging the S-spin signals to provide an averaged S-spin nuclear induction signal from a single I-spin polarization.
Claim 20
Dependent Claim
23 words
The method of claim 1 comprising, in addition, Fourier transforming of said averaged S-spins signal to provide the frequency spectrum of the S-spins.
Claim 21
Dependent Claim
90 words
The method of claim 1 comprising, in addition, applying said I-spins field excitation a plurality of times corresponding to the number of S-spins field excitations, said I-spins excitation being gradually applied to avoid destroying the I-spin order and of substantially full magnitude before said S-spin excitation is removed, said I-spins excitations being gradually reduced to substantially zero amplitude after said free induction decay signal is detected and before said S-spin excitation is applied again, the amplitude of said I-spins excitation being sufficient to remove the dipolar coupling of the I-spins.
Claim 22
Dependent Claim
90 words
The method of claim 2 comprising, in addition, applying said I-spins field excitation a plurality of times corresponding to the number of S-spins field excitations, said I-spins excitation being gradually applied to avoid destroying the I-spin order and of substantially full magnitude before said S-spin excitation is removed, said I-spins excitations being gradually reduced to substantially zero amplitude after said free induction decay signal is detected and before said S-spin excitation is applied again, the amplitude of said I-spins excitation being sufficient to remove the dipolar coupling of the I-spins.
Claim 23
Dependent Claim
40 words
The method of claim 1 comprising, in addition, maintaining said I-spin r.f. magnetic field during the time said S-spin r.f. magnetic field is applied, and adiabatically reducing said I-spin field to zero before said S-spin field is abruptly turned off.
Claim 24
Dependent Claim
40 words
The method of claim 1 comprising, in addition, maintaining said I-spin r.f. magnetic field during the time said S-spin r.f. magnetic field is applied, and adiabatically reducing said I-spin field to zero before said S-spin field is abruptly turned off.
Claim 25
Dependent Claim
139 words
The method of claim 1 comprising, in addition, adiabatically reducing the amplitude of the I-spins r.f. magnetic field when said S-spins magnetic field excitation is applied, adiabatically increasing the amplitude of the I-spins r.f. magnetic field prior to turning off said S-spins field excitation, maintaining said increased amplitude of said I-spins r.f. magnetic field during the time said S-spins free induction decay signal is being detected in order to remove the dipolar coupling of the I-spins, adiabatically reducing said I-spins r.f. magnetic field to zero after said S-spins signals are not being detected, applying said S-spins field excitation a plurality of times, the amplitude of said I-spins field excitation during said plurality of S-spin excitation fields being at the amplitudes recited previously during and between said S-spin excitation fields with adiabatic changes in said amplitudes of the I-spin fields.
Claim 26
Dependent Claim
139 words
The method of claim 2 comprising, in addition, adiabatically reducing the amplitude of the I-spins r.f. magnetic field when said S-spins magnetic field excitation is applied, adiabatically increasing the amplitude of the I-spins r.f. magnetic field prior to turning off said S-spins field excitation, maintaining said increased amplitude of said I-spins r.f. magnetic field during the time said S-spins free induction decay signal is being detected in order to remove the dipolar coupling of the I-spins, adiabatically reducing said I-spins r.f. magnetic field to zero after said S-spins signals are not being detected, applying said S-spins fIeld excitation a plurality of times, the amplitude of said I-spins field excitation during said plurality of S-spin excitation fields being at the amplitudes recited previously during and between said S-spin excitation fields with adiabatic changes in said amplitudes of the I-spin fields.
Claim 27
Dependent Claim
44 words
The method of claim 20 wherein said I-spin magnetic field amplitude and the S-spin magnetic field amplitude during the time said S-spins field is applied satisfy the Hartmann-Hahn condition, gamma IH1(I) gamma sH1(S), for a time sufficient to most rapidly establish spin thermodynamic equilibrium.
Claim 28
Dependent Claim
44 words
The method of claim 21 wherein said I-spin magnetic field amplitude and the S-spin magnetic field amplitude during the time said S-spins field is applied satisfy the Hartmann-Hahn condition, gamma IH1(I) gamma sH1(S), for a time sufficient to most rapidly establish spin thermodynamic equilibrium.
Claim 29
Dependent Claim
86 words
The method of claim 1 comprising, in addition, applying the sequence of radio frequency magnetic fields at the Larmor frequency of the I-spins by spin-locking by applying a 90* pulse followed by a 90* phase shift in the frequency of the radio frequency carrier which is continuously applied, applying and removing said S-spins excitation a plurality of times, detecting said S-spins free induction decay field after each removal to provide a plurality of signals, averaging the S-spin signals to provide an averaged S-spin nuclear induction signal.
Claim 30
Dependent Claim
87 words
The method of claim 2 comprising, in addition, applying the sequence of radio frequency magnetic fields at the Larmor frequency of the I-spins by spin-locking by applying a 90* pulse followed by a 90-degree phase shift in the frequency of the radio frequency carrier which is continuously applied, which applying and removing said S-spins excitation a plurality of times, detecting said S-spins free induction decay field after each removal to provide a plurality of signals, averaging the S-spin signals to provide an averaged S-spin nuclear induction signal.
Claim 31
Dependent Claim
38 words
The method of claim 1 in which the sequence of radio frequency magnetic fields at the Larmor frequency of the I-spins comprises spin-locking by applying a 90* pulse followed by a 90* phase shift in the frequency carrier.
Claim 32
Dependent Claim
38 words
The method of claim 2 in which the sequence of radio frequency magnetic fields at the Larmor frequency of the I-spins comprises spin-locking by applying a 90* pulse followed by a 90* phase shift in the frequency carrier.
Claim 33
Dependent Claim
60 words
The method of claim 1 in which the sequence of radio frequency magnetic fields at the Larmor frequency of the I-spins comprises spin-locking followed by adiabatic demagnetization by applying a 90* pulse followed by a 90*phase shift in the radio frequency carrier followed by a gradual shutting off of the carrier in a time long compared to 1/ gamma 1H1.
Claim 34
Dependent Claim
61 words
The method of claim 2 in which the sequence of radio frequency magnetic fields at the Larmor frequency of the I-spins comprises spin-locking followed by adiabatic demagnetization by applying a 90* pulse followed by a 90* phase shift in the radio frequency carrier followed by a gradual shutting off of the carrier in a time long compared to 1/ gamma 1H1.
Claim 35
Dependent Claim
59 words
The method of claim 1 in which the sequence of radio frequency magnetic fields at the Larmor frequency of the I-spins comprises pulsed preparation of the dipolar state by applying a first 90* pulse followed by a 45*pulse, said 45* pulse follows the 90* pulse by a time on the order of T2 and is phase shifted by 90*.
Claim 36
Dependent Claim
60 words
The method of claim 2 in which the sequence of radio frequency magnetic fields at the Larmor frequency of the I-spins comprises pulsed preparation of the dipolar state by applying a first 90* pulse followed by a 45*pulse, said 45* pulse follows the 90* pulse by a time on the order of T2 and is phase shifted by 90 degrees.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-02-11 | 1977-08-13 | 1978-02-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-02-11 | 1981-08-13 | 1982-02-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-02-11 | 1985-08-13 | 1986-02-12 | $7700.00 | Window Closed / Lapsed |