DE1966801B2 - Magnetic core resonance spectrometer - for measuring gyro magnetic resonances - Google Patents

Abstract

The analysed specimen is exposed simultaneously to a constant magnetic field and a h.f. magnetic alternating field and for obtaining simultaneous resonance signals in different resonance regions means are provided for alternating modulation of both fields at least two different frequencies.

Description

shifted the value 4 <o _m and then added to the output of the analog / digital converter 22. The added resonance signals are then displayed on a playback device 21
This gives a signal intensity which is twice as great as in the known method, the signal-to-noise ratio increasing to V 2. If more modulation frequencies are used, the signal-to-noise ratio can be improved even further.

For this purpose 2 Βίε «drawings

Claims (3)

\ ! 9 66 801 ^u 1 2 by the respective, by the distance between the modul Claim: lationsf ^ jejizeffgegsbenenF ^ quenzabstendsover- ^{r is} pushed that each at the same frequency occurring resonance signals are added. Method of measuring the gyromagnetic S The advantage achieved with the invention Resonance according to the sideband method, which consists in the fact that with the same measurement time as the • the polarizing magnetic field or the high-frequency method, the signal-to-noise ratio quente alternating field is swept, so that the factor Ϋ2 is reduced for each resonance signal. characterized that can improve the better. Signal-to-noise ratio the polarizing to The invention is to be explained with reference to the figures near the magnetic field and the high-frequency alternating field. It shows
with at least two frequencies (co _mi or, Ss _4n ^) Fig. 1 is a block diagram of a device with is modulated, the frequency spacing OdO ₁ J, which can be used to measure the gyromagnetic resonance, small compared to the width of the spectrum. 2 modulation frequency forms that are used in the is selected) so that the spectrum in the Wobbe- 15 embodiment in Fig. 1 for application kom-IuEg according to the number of modulation modes and sidebands essentially whole and the same- Fig. 3 resonance signals, which is passed through several times with the Vonich that each of the tion in Fig. 1 can be achieved,
Re generated by the modulation sidebands. In the embodiment of FIG stored sonanzsignaie and then to generate μ sample in a by means of an electromagnet 2 the respective constant magnetic field polarizing by the distance between the modules, lationsfrequenzen given frequency spacing so the electromagnet 2 is shifted by an unspecified is that each fed with the same provided energy source. A high frequency frequency Occurring resonance signals added coil 3 superimposed on the sample 1 a high frequency field, will. »5 being the required high frequency of one High frequency transmitter 4 is supplied via an attenuator 5 and a bridge detector 6. A modulation coil pair la and 7ft, which are arranged coaxially to the constant magnetic field, is acted upon by 30 low-frequency oscillators 8 and 9 via gate circuits 10 and 11 with modulation frequencies w _m and u) _m of, for example, 4 kHz and 5 kHz. A pulse generator 12 controls the gate The invention relates to a method for measuring lines 10 and 11 in such a way that they modulate the gyromagnetic resonance according to the side 35 frequencies ω _ηι and <o _mt alternating with the moduband method, in which the polarizing magnetization coils la and 7 ft let through (see. Fig. 2). field or the high-frequency alternating field wobbled By wobbling the constant field, resonances are will. nanzsignale / ₍ ± w _mi and / _f ± a> _mt of sample 1 generated From NMR and EPR Spectroscopy, Pergamon and in a high-frequency amplifier 13 via Press 1960, pp. 180 and 181, it is known that the bridge detector 6 is fed into it. /, is the frequency of the investigating NMR spectrum by Wobbein and high-frequency transmitter 4 and is, for example, modulation of the polarizing magnetic DC 60 MHz. The amplified resonance signals are scanned in the field. In addition, a high-frequency mixer 14 is then fed from Exp., The Techn. D. Phys., XI, 1963, p. 109 to 113, known, at the same time the high frequency /, from the high frequency the magnetic constant field with two frequencies to 45 sender 4 receives as a reference signal. The output signals modulate, whereby the one resulting from this then have the frequency w _ml and ω ™ · This out-sideband signal is used as a manipulated variable and output signals are routed to gate damage 15 and 16 by sweeping the other modulation frequency, which is controlled by the pulse generator 12 in this way investigating spectrum with the other are that when the modulation frequency is supplied, the sideband signal is swept over. In this case, 50 co _ml results in the gate circuit 15 and when the Mosich is fed in has the disadvantage that the signal-to-noise ratio of the resodulation frequency w _m2 the gate circuit 16 is open, and nanzsignale is relatively low. while the other gate circuit is blocked. Accordingly, the object of the invention is to provide a solution. The output signals of the gate circuits are drive to the measurement of the gyromagnetic resonance phase detectors 19 and 20 supplied after they show, in which the resonance signals with increased 55 in audio frequency amplifiers 17 and 18 amplified wor-signal, noise ratio can be received. who are. At the same time, the modulation This object is achieved in the method of the initially mentioned frequencies w _ml and w _m of the low frequency type according to the invention in that oscillators 8 and 9 are fed to the phase detectors 19 and 20 as reference signals to improve the signal-to-noise ratio,
the polarizing magnetic field or the high-frequency 60 If one chooses the difference Δ m _m between the alternating field with at least two frequencies modulation frequencies ω _η1 and w _m so that it is very lated, the frequency spacing of which is small in comparison, close to each other (Fig. 3) , the result is that the width of the spectrum is selected so that for the spectrum to be examined, for example, the spectrum during the wobble corresponding to the A and B resonance signals. The resonance signals are number of modulation sidebands essentially 65 which a computer 24 via analog-to-digital converter 22 passes through completely and simultaneously several times that and 23 are fed in. After each of the resonance signals generated by the modulation sidebands has been stored in the analog-digital resonance signals and then converter 23, the output of this converter 23 is converted