DE1673185C - Device for decoupling the spins of two groups of gyromagnetic particles - Google Patents

Description

2. Device according to claim 1, thereby changing the direction according to the older proposal so that indicates that the two particle groups in each case mean that the spin-spin decoupling is more effective Cores are. is performed so that closely spaced in terms of frequency

3. Apparatus according to claim 1 or 2, characterized in that groups can be decoupled without the fact that the three magnetic alternating atomic parts of the group to be observed are from the fields high-frequency fields and the two desired orientations are tilted out, and decoupling alternating fields H ₂ and H _3, in which shifts in the resonance frequency also have amplitudes, than the excitation alternation of the observed group due to the decoupling field H ₁ . field H _{2 are} effectively avoided.

4. Apparatus according to claim 3, characterized in that the two decoupling solutions to this object according to the invention, the alternating fields H ₂ and H ₃ essentially the same 50 sequences ω ₂ and a> _{3 of} the two Have decoupling alternating strength and the frequency of the fields H ₂ and H ₃ to prevent a recoupling of the alternating excitation field H ₁ around essentially the same of the spins of the two particle groups selected so that frequencies differ. the frequency W _{1 of} the alternating excitation field H ₁ between

5. Device according to one of claims 1 see these two frequencies lies.

to 4, characterized in that at least ₅₅ "The spin of the observed group precesses at

one of the alternating magnetic fields of such a choice of frequencies neither with the field H ₂

High frequency generator is generated, the magne- still with H ₃ , but initially remains in the direction of the

table polarization field H _{0 is} modulated and that polarization field H ₀ polarizes or precesses after

the modulation frequency in turn frequenzmodu- excitation with the excitation field H ₁ with it

is lated. 60 frequency ω! around the field vector of the polarization field H ₀ .

Various constituents come into question as particle groups when the device is used in connection with the investigation of the magnetic

The invention relates to a device for entic 65 magnetic resonance are commonly coupled as particles chosen the spins of a group of gyromagnetic wise nuclei.

Particles from the spins of a group of to- The three alternating magnetic fields can high observer be gyromagnetic particles in a frequency fields, preferably then have the

3 4

two decoupling alternating fields H ₂ and H ₃ larger visible no / Z ₀ field and is in the direction of the

Amplitudes than the alternating excitation field H ₁ . Polarized Ins- / Z ₂ -field, which is right-wound to the PoIa-

In particular, the two decoupling-alternation fields H ₀ lie. Because the

feider ZZ ₂ and / Z ₃ essentially the same strength and now lent atomic parts no static spin compo-

differ in frequency from the excitation 5 in the // "direction, they are of

Alternating field H ₁ at essentially the same frequencies, neighboring atomic parts that are aligned with H _0,

so that the two alternating decoupling fields are decoupled. But if the neighboring atomic parts

knowledge that is symmetrical to the excitation field are close to resonance with ω ₂ , they align with

and its effect on the observed vector sum H _ett , which is the vector sum of

Particles also strictly theoretically pick up. Depending on the xo H _a and H ₂ , where

The substance to be examined must have this symmetry - Co ₂

condition more or less strictly adhered to H _a - H ₀ -,

will. '

At least one of the alternating magnetic fields with γ as the gyromagnetic ratio of the atoms is generated by a high frequency generator when 15 parts. From this it follows that although the field H ₂ aligns a first group modulates the magnetic polarization field H ₀ in its direction, this modulation frequency can in turn be frequency modulated with H _e tt to be frequency-modulated on the group to be observed Way can be misaligned, which also has a component at least another of the magnetic alternating fields that are statically coupled to the first group to generate, which has the advantage that it is not necessarily agile as a result of the coherent precession is to add three high frequency generators to the two groups. After the optimal theft, which has only been achieved in terms of coupling conditions to a small extent, each tries to deviate markedly. _{] I} increase the field strength of H ₂ the atomic

The invention is intended to recouple parts of the two groups in more detail with reference to the drawing. With others

be explained; it shows as words when the angle between the vectors Hm

F i g. 1 is a block diagram of an inventive and H ₂ becomes smaller, the spin coupling between

Device, the groups aligned with H _e ti and H _{2 larger.}

F i g. 2 a and 2 b vector diagrams for explanation It should be mentioned that if the size is changed

of the invention and the vector ZZ _e ft relative to the vector H _a the resonance

F i g. 3 a block diagram of another frequency of the observed group is shifted,

embodiment of the invention. According to one embodiment of the invention

According to FIG. 1 is a probe 10 that uses one to a third RF generator 34 to generate a second

sample to be analyzed contains, between the poles of a decoupling magnetic field H ₃ to the coil of the probe

Magnet 12 arranged to deliver a polarizing magnet 10 with a frequency and size that the

field H ₀ of, for example, 14,000 Gauss. A response of the observed group with the // etf-rcld

HF generator 14 supplies an HF signal with which cancels out, so that the undesired tilting of the

Larmor frequency toj of the atomic parts or nuclei from observed nuclei to the H ₂ vector is eliminated

for example 60 MHz and 0.1 milligauss to one (see FIG. 2b). The FeIdZZ ₃ can be one size

Have coil in probe 10 perpendicular to the polarization of 5 milligauss, the same as H ₂ , and one

field H ₀ . A modulation oscillator 16 supplies a frequency ω ₃ of 60 MHz-100 Hz. Self-evident

low frequency current to a bias current coil 18, which can be a different size and frequency than the _{lent cu 3}

encompasses the probe so that the polarization magnet should have, for example, specified values, but should

field H _{0 is} modulated on the probe and the Re- in any case a compensation and compensation

the resonance range of the nuclei is passed through several times. field Hi " deliver that the tilting effect of the

The coupling field H ₂ generated by the precessing nuclei on the observed group induces a counteracting alternating field in a receiver coil. In this way there is a substantial voltage that is provided to a preamplifier 20 and then improved spin decoupling of the second group of to an RF amplifier 22. That was achieved by the observed group. With a suitably strong signal, the resonance of the RF signal from generator 14 can also be detected in a phase detector 24 with a magnitude and frequency of H _3. The 5 ° frequency of the observed group can be shifted back to its low-frequency output of, for example, 2000 Hz, because it is then amplified in an AF amplifier 26 and the effect of H ₂ on the position of the line is eliminated,
the amplified signal is generated in an LF phase detector. Another embodiment of the invention is shown in FIG. 28 with the modulation signal from the oscillator 16 FIG. 3 illustrates where only a single RF is detected. The direct current signal thus obtained is used 55 generator 14 to record an alternating field H ₁ in a recorder 30. with a frequency ω, with which the atomic

A strong alternating field H ₂ will be oriented perpendicular to parts of H ₀ in the polishing field H _0. A

applied by means of an HF generator 32, which also supplies a signal to the first modulation oscillator 36

Coil of the probe 10 is coupled. The HF-FeIdZZ _{2 of} a frequency w _m , which is through a pole piece 38

has a frequency close to the Larmor frequency, 60 is given to the sample so that a sideband

for example 60 MHz plus 100 Hz, and a W ₁ ± co _m , is generated and in this sideband

5 milligauss in size. This strong field ZZ ₂ the atomic parts of interest are observed,

effectively decouples the secondary cores from the A second modulation oscillator 40 provides a module

Cores of the observed group and is therefore a lation signal of the frequency w _m2 via a coil 42

referred to as the decoupling field. 65 with sufficient amplitude to decouple the

Fig. 2a shows the two different groups contained in the sample of the decoupled group

seen magnetic field in a rotating pen _{with a> 2.} However, this modulation works

Coordinate system. The decoupled group sees the same tipping effect as when the

Decoupling field H _{2 was} determined, which in the embodiment according to F i g. 1 was supplied by the RF generator 32. In order to compensate for such a tilting effect, a third modulation oscillator 44 is used with which a second decoupling signal with the frequency w _ms is supplied by a coil 46, which serves to effectively decouple the atomic parts of the two groups.

In one embodiment of such a sideband system, the HF generator 14 was operated at 60 MHz, the modulation oscillator 36 supplied 5 kHz, so that a sideband of 60 005 kHz resulted with which the atomic parts of interest were observed. The modulation oscillator 40 supplies a signal of 5100 Hz, so that a sideband signal of 60 005.1 kHz results, with which decoupling takes place. A second decoupling signal of 4900 Hz from the modulation oscillator 44 results in a further signal of 60 004.9 kHz. This second decoupling signal serves to compensate for the first decoupling signal so that the atomic parts to be observed are essentially _{aligned with the / Z 0} field. In this way, an improved decoupling with a corresponding improvement in the resolution of the observed spectral range is achieved.

The gyromagnetic device according to the invention is not limited to a specific embodiment or the parameters mentioned above. For example, the second decoupling field H ₃ that provides H ' _{a (} can be derived as a sideband of H ₂ at twice the frequency of the field modulation. Thus, H ₂ and H ₃ would serve to effectively decouple the second group. A differential -Gain control can be used to

ίο to change H ₂ and H ₃ , but to keep the combined Erit coupling effect constant. At a certain value of H ₂ and H ₃ , a compensation for the effective effect of H ₂ and H ₃ on the observed group is achieved. If two core groups are decoupled at the same time by two // ₂ fields with separate frequencies, only a single i / ₃ compensation field needs to be used.

Furthermore, the device can be a combination

of the HF generators according to the embodiment

ao F i g. 1 and the modulation oscillators according to FIG. 3 contain. The invention can also be used without the LF phase detector, the modulation oscillator connected to it and running the LF amplifier when the output from phase detector 24 can be fed directly to the recorder.

1 sheet of drawings

Claims (1)

ι 2 sample, with a device for generating a patent claims: polarizing magnetic field H0, a probe for: recording the sample with the two spin-coupled 1. Device for decoupling the spins of a group in the polarization field H ₀ , at least a group of gyromagnetic particles from the 5 a transmitter with which a magnetic excitation spins of a group of gyro-alternating field H ₁ to be observed is applied to the sample, a magnetic panic in a sample, with an Emp device coupled via the probe to the transmitter for generating a polarizing catcher, the coupling between the transmitter magnetic field H ₀ , a probe for receiving the and the receiver through the gyromagnetic sample with the two being spin-coupled Groups io resonance of the particle group to be observed in the polarization field H ₀ , at least one is changed, a device for wobble of the transmitter, with which a magnetic excitation ratio of the transmitter frequency to the strength of the alternating field H _{1 is applied} to the sample, a polarization field H ₀ by the gyromagnetic spect. coupled to the transmitter via the probe ral area of the particle group to be observed, receiver, the coupling between the 15 of a detector device, with which the receiver transmitter and the receiver is determined by the gyro-approached amount of energy, in order to change the magnetic resonance of the observed gyromagnetic spectral lines of the particle group to be observed , a device to represent particle group as a function of the wobble to the wobble of the ratio of the transmitter frequency, and a device with which a to the strength of the polarization field H ₀ by the ao magnetic decoupling alternating field H _{2 is applied} to the gyromagnetic spectral range of the sample to be loaded . observing particle group, a detector device, such a direction has already been proposed to equip the known device to which the receiver has been received with a device to determine the amount of energy to equip the gyro, with which a second magnetic decoupling magnetic spectral lines of the as to be observed Lungs-alternating field H _{3 is} generated and applied to the sample at -particle group depending on the wobble (German patent 1 296 417).
a device with which a magnetic decoupling alternating field H _{2 is applied} to the sample field H ₂ at a frequency in the immediate aftermath, and a device with which the resonance frequency of the observed a second magnetic decoupling Alternating group causes both a resonance shift field H _{3 is} generated and applied to the sample, the frequency of the observed group and one characterized in that the free re-coupling of the spins. The spin system of the entquenzen 1> ₂ and ω _{3 of} the two decoupling-coupled groups is aligned with the second decoupling alternating fields H _t and H ₃ to prevent a coupling field H ₂ , but recoupling of the spins of the two particle groups 35 can occur Recoupling occurs because the spins of the are chosen so that the frequency to, of the observed group tilt away from H ₀ after the alternating excitation field H ₁ between these two also precesses with H _2.
Frequencies lies. The object of the invention is therefore to