DE1773746C3 - Bimodal cavity resonator for spectrometers for gyromagnetic resonance - Google Patents

Description

3. Bimodal cavity resonator after connecting only the other of the two resonance modes Claim 1 or 2, characterized in that the one can be excited, and the one with devices for tuning only one of the two resonance modes leads to the resonance mode that can be excited in it Is cavity area (3 or 4) with units. With such a further developed hollow directions (7,8) for coupling the respective space resonator according to the invention, the superleon resonance mode apply in the respective cavity gate, with regard to the one resonance mode aucr rich (3 or 4) is provided. for the other.

4. Bimodal cavity resonator according to An In principle, the coupling of the respective claim 1, 2 or 3, characterized in that 35 resonance mode in the same way as with the a device (13, 14) for adjusting the known bimodal cavity resonator However, coupling between the two resonance modes is expediently only one in each case is provided in the first cavity region (2). of the two resonance modes leading Hohlraumbe

5. Bimodal cavity resonator after a rich with facilities for coupling the respective of claims 1 to 4, characterized in that 40 gene resonance mode in the respective Hohlraumbe that a device (41, 55, 56, 58; 52, 55, 57, richly provided.

59) is provided, with which it is ensured that in principle the two modes of resonance are

the frequency of the microwave excitation, through which orthogonal and thus decoupled from each other. Despite

depending on one of the two resonance modes, a cross coupling between the two is excited, the changes in the resonance frequency 45 resonance modes occur, and to trigger them

sequence of the respective cavity area is expedient according to a development

a tuning of this area follows. the invention a device for setting de

6. Bimodal cavity resonator after coupling between the two resonance modes in Claim 5, characterized in that the ab- first cavity area is arranged. Tuning device (12) for the third cavity - 5 ° bimodal cavity resonators are at Dop area (4) contains a device (69) with which pelresonance examinations are required in which dl the resonance frequency of the resonance mode of the frequency of the one resonance mode is fixed third cavity area (4) and the frequency of the other resonance module is swept. is changed. The bimodal according to the invention

55 Cavity resonator can for easier implementation of such investigations according to a further Education of the invention in such a way that a device is provided with the da

care is taken that the frequency of the microwaves

⁶ <i excitation, by which one of the two resonance modes is excited in each case, following the changes in the resonance frequency of the respective cavity areas when tuning this area. Since it is expediently provided in addition

The invention relates to a bimodal cavity - 65 that the tuning device for the third cavity ionator for spectrometer for gyromagnetic Reraumbereich contains a device with the di nance, which has a first cavity region, resonance frequency of the resonance mode of the third the two orthogonal resonance modes excitable cavity area is automatically swept through

3 4

The invention will hereinafter have such a length that the 7 £ ₁₀₃ mode resulted

Description in conjunction with the drawings will i. that is, they have a total length of three

explained in more detail; it shows halves of a guide wavelength. Tuning screw

1 is a schematic perspective illustration 11 and 12 are in the non-common part

ment of a bimodal cavity, 5 of the cavity 3 and 4 respectively arranged around the two

F i g. Figure 2 shows another embodiment of tuning resonance modes. The tuning screws

F i g. 3 a third embodiment, 11 and 12 can be conductive or made of a dielectric

4 shows a block diagram einr be ^r spectrometer see material, usually by the cavity in

paramagnetic resonance and way to tune.

Fig. 5 is a block diagram of another Spectro: o Two sets of adjusting screws 13 and 14 are in the metered embodiment. common part 2 provided to the Kreuzkoppln Fi ^. 1 shows a bimodal cavity 1 between the two resonance modes within. The cavity resonator 1 consists of one of the bimodal cavities 1 to be extinguished. The central, common part 2 of the two resonance screws 13 are in the places of maximum vibration modes. Two rectangular electrical fields of the two modes are arranged and waveguide parts 3 and 4 are made of resistance material at different ends, while those are coupled to the central, common part 2. Screws 14 in the areas of maximum ma-The rectangular waveguide sections 3 and 4 of the magnetic field of the two modes are arranged cavity resonator 1 can each only have one of the and consist of a conductive material to guide the resonance modes and are around ^Q 0 ^D to each other 20 reactive components The waveguide structure is drawn out so that they do not share the common parts of the surface. In a typical embodiment, form the cavity for the two modes of resonance. Cavity according to Fi g. 1, the end walls of the composite Hohlraumre- is bein eat for operation in the AT-band of the composite cavity 1 has sonators 1 are defined by the transverse walls 5 and 6 Defi- a quality factor Q of 8000 for each of the two defined, that of the outer ends Waveguide section 25 modes, and complete the Kreuzkopp'ring between the two nen3 and 4 respectively. Coupling irises 7 and 8 modes were set so that cross coupling are arranged in the transverse walls 5 and 6, respectively, in order to obtain from -80 dB.

Vibrational energy from cavity 1 to the hollow In Fig. 2, another bimodal cavity is shown conductors outside of the composite bimodal similar to the structure of FIG. To be coupled in the we-Resonator 1. 30 laterally this cavity is the same as that according to The central section 2 of the assembled bi- F i g. 1, only that, according to the construction of the modal cavity 1, it has an approximately square cross-section, it is necessary that only one of the resonance _{modes is cut off by two dominant TE 10.} , - modes in ortho slimmable. The non-common part for the fixed gonal relationship to one another, namely coordinated mode, is therefore omitted, namely between the orthogonally arranged cinan waveguide sections4 and through a conductive wall of the opposite side walls. The middle 15 is replaced with a central screen 16 with which part 2 has end walls 9 and 9 ', which are separated from one another by an integral number of half wavelengths coupled to an E-bend section of a waveguide 17. The non-common part of the tunable and defined by the wall structure, ren resonance mode, which is formed by the rectangular hollow which the wide walls of the waveguide sections 3 40 conductor section 3, is connected to the side walls of the middle section 2 by means of a short and 4 length coaxial line 19 with an E-bend hollow band. The rectangular waveguides 3 and 4 are coupled in the conductor section 18, which leads through the wide wall of the orientation shown beyond the borderline E-Bicgungs waveguide 18 and the narrow frequency for the mode whose electrical field par wall of the waveguide section 3. An antenna allele to the broad walls of the waveguide 3 or 4 45 21, which is due to the extension of the central conductor. Coaxial line 19 is formed, couples signals from the top and bottom of the central section 2 to the e-bend conductor 18 in the rectangular hollow openings in the middle and to conductor 3 via an inductive coupling loop 22.
two conductive tubes 10 and 10 ', which This coupling arrangement is in the USA.-Pamit the openings are aligned and described from 50 tentschrift 32 14 684. Extend the tuning cavity away. The tubes 10 and 10 'bil screw 11, with which the tunable resonance mode is tuned to two circular waveguides beyond the limit dus, is available in the waveguide section 3 frequency for the microwave energy in the waveguide 1 through a central opening in the end termination die The material sample to be examined is placed in the cavity wall 5. The composite cavity structure is inserted in such a way that it contains a first tunable resonance of the tubes 10 and 10 'through the OfT-55 turl. The mode section, which is formed by the waveguide section 3 ge area of the sample within the central part 2 of the, and a second central section 2, unc resonator is the orthogonal magnetic Mi- is in 7 £ _10. , - mode in resonance. Exposed to fixed microwave fields H ₂ and H _y . For under-tuned resonance modes, the central visit is occupied by the paramagnetic electron resonance 60, and in the 7E ₁₀₂ mode, the cavity 1 is preferably in a magnetic resonance.

see polarization constant field // "in the way- In F i g. .1 is a further embodiment Darge

ordered that both H _z and / 7 _Λ . Components provides; more precisely, has the bimodal cavity

a central cylindrical section 2 normal to the direction of the magnetic polarization resonator 1

tionfcldes H _n have. 65 which can lead to two orthogonal modes of resonance

In one embodiment of the cavity 1, for example, there are two cylindrical 7'E ₁ , modes. Two zy

the common and non-common areas of cylindrical sections of waveguides 3 and 4 are ai

dimensioned together for each mode so that they one of the two ends of the central waveguide section:

connected. Each of the two waveguide sections 3 and 4 has a conductive partition 25 or 26, which extend diametrically across the conductor so that it is divided into two parallel semi-cylindrical sections is divided. The partition walls 25 and 26 are oriented in planes orthogonal to one another, so that each of the two cylindrical waveguide sections 3 and 4 for the other mode on the other side the cut-off frequency and only one of the two resonance modes excluding the other resonance mode can lead.

The waveguide sections 3 and 4 are closed at their outer ends with conductive walls 27 and 28, respectively. Coupling panels 29 and 31 are arranged centrally in the conductive walls 27 and 28. Rectangular waveguide sections 32 and 33 are coupled to the cylindrical waveguide sections 3 and 4, respectively, with the coupling diaphragms 29 and 31. The waveguide sections 32 and 33 are oriented orthogonally to one another, the width walls each lying parallel to the partition walls 25 and 26, respectively. The composite bimodal cavity resonator 1 thus has two resonance mode structures with a common area 2 and separate, non-common areas 3 and 4, respectively. In a preferred embodiment, the two resonance mode structures are dimensioned _{for resonance in the cylindrical TE m mode.}

Tuning screws 11 and 12 are provided to tune each of the two separate resonance modes, by changing the fields in the non-common parts 3 and 4 respectively. The one to be analyzed Sample is placed in the center of the common region by being coaxial through it Pipes 10 and 10 'is guided in the central part 2.

In Fig. 4 is a spectrometer for paramagnetic Resonance shown in the microwave range. The bimodal sample cavity 1 is one-arm a microwave bridge 35 coupled. A reflex klystronic oscillator 36 is connected to another arm of the Bridge couples and feeds power into the through an isolator 37 and a variable damper 38 Bridge a. The arm of the bridge opposite the arm containing the sample cavity 1 is terminated with a resistive load 39, and the other arm of the bridge contains a diode detector 41. A variable tuning element 42 is provided in the sample cavity arm for coupling with to adjust the cavity 1.

The other mode of the bimodal cavity 1 is coupled to a second bridge 44 for the pump microwave excitation to put to the test. The bridge 44 contains a circulator 45 with three openings, the sample cavity 1 being connected to an opening. The pump microwave energy is supplied to the bridge 44 with a reflex klystronic oscillator 46 which is connected to another opening of the Circulator 45 is connected via a waveguide containing two insulators 47 and 48, a variable one Damper 49 and a diode switch 51. A diode detector 52 is in a further arm of the circulator 45 is arranged.

The klystronic oscillators 36 and 46 are each coupled to the resonance frequency of the associated Locked resonance modes of the bimodal cavity 1 by means of an automatic frequency control channel. The automatic frequency control channel contains an AFR modulator that controls the reflector voltage of the klystrons 36 and 46 are modulated with a suitable audio frequency, for example 10 kHz. If the center frequency of the K'ystron oscillator 36 or 46 is different from the resonance frequency of the respective orthogonal Mode deviates in the bimodal cavity 1, becomes a component of the AFR modulation frequency detected in the detectors 41 and 52, respectively. These AFR modulation frequencies are used with Amplifiers 56 and 57 amplified and the output ίο to an input of a phase-sensitive detector 58 or 59, in which it is compared with a part of the AFR modulation signal, which is derived from the AFR modulator 55. The output of the phase sensitive detectors 58 and 59 forms two offset DC voltages to be supplied to the klystronic oscillators 36 and 46, respectively are applied to their center frequencies on the resonance frequencies of the respective resonance modes of the bimodal cavity 1 to match. The off-tuning range, which is for the reflex klystronic oscillators 36 and 46 typically exceed the reflector mode tuning range for the cavity mode the reflex klystron. Accordingly, mechanical tuners (not shown) are provided, to tune the klystron cavities, not shown. The mechanical tuners ensure that the cavity modes of the klystrons are matched to the frequency of the reflector mode, so that the reflector mode can follow the respective mode of the bimodal cavity 1.

The spectrometer according to FIG. 4 also has an observation channel to the paramagnetic Observe electron resonance of the sample via the other resonance mode of the cavity 1. More accurate said, a microwave signal derived from klystron 36 excites the observation resonance mode of the cavity 1, which is coupled to the sample in order to excite its resonance. If there is a response the observation cavity mode coupled to the sample reflects both a reactive one as well as an absorption component in the bridge 35.

In one mode of operation of the spectrometer according to FIG. 4, the polarizing magnetic field H _{0 is} modulated by means of a modulation coil 61 which is excited with a current in the upper audio frequency range, for example 100 kHz, which is supplied by an oscillator 62 via a switch 63. The modulation of the polarization field provides a modulation component of the paramagnetic resonance signal at the modulation frequency of 100 kHz. This modulation component is amplified in amplifier 56 and applied to one terminal of phase sensitive detector 64 where it is compared with a portion of the field modulation signal derived from oscillator 62 to provide a paramagnetic resonance output signal. The resonance output signal is fed to an input of a recorder 65, where it is recorded as a function of a wobble of the magnetic polarization constant field H ₀ , which is held by a current from a field wobble generator 66, which is fed into a field wobble coil 67 will. The writer 65 provides a spectrum of the paramagnetic electron resonance of the analyzed sample. When field modulation is used, i the recorded spectrum is the first derivative d <paramagnetic resonance signal.

7 8

Most samples for paramagnetic electrodes and for obtaining hyperfine structure couplings in common resonance yield a relatively complicated spectrum of paramagnetic materials, with many overlapping lines. Instead of wobbling the magnetic field H ₀ , it was established that such spectra can often be increased simply by multiplying the observation microwave frequency by performing a double resonance of the pump microwave frequency through the sample. More precisely, the spectrum will wobble, the observation line can be continuously observed with the pump-resonance line using the pump-resonance line, while the resonance mode of the cavity is delivered to the sample, while the pump frequency is passed through the remaining part of the cavity's observation mode - Spectrum is swept, and double resonance is coupled. The pump logic is monitored with a certain io gnale via the modulation who modulates the modulation frequency, and that which is coupled to the resonance line observed by the pump microcunivcau in the observed signal of the paramagnetic resonance. This is achieved in any component of the modulation spectrometer according to FIG. 4 in that the frequency which has been transmitted into the observed resonance output wobble generator 66 with switch 68 is monitored and detected. The Spck motor 69 is switched, which is coupled to the tuning section 12 only at these resonance lines. The switch 63 is also shown, which contains the pump modulation frequency switched in such a way that the modulation frequency of 100th kHz is applied from the oscillator 62 to the diode switch 51

The pumping mode of the cavity is set to one in order to modulate the amplitude of the pumping energy.

Frequency set that depends on the frequency of the observation. The pump energy is coordinated by

operating mode by a predetermined amount means that the pumping mode of the cavity 1 goes through

is distant, and the polarization field is wobbled, is correct, because the AFR ensures that the

to get a spectrum. It is thus often possible to pump frequency the pump mode of the cavity 1

borrowed to follow the obtained spectrum of the sample considerably. The spectrum recorded in the recorder 65

simplify. 25 is then considerably simplified.

The spectrometer according to FIG. 4 can be used for recording. 5 is another double resonance spectra represented by the electron-electron double resonance da- meter. The spectrometer is essentially through be set so that the switch 63 is constructed in the same way as that according to FIG. 4, only that lent, so that the 100 kHz oscillator 62 with the output of the 100 kHz oscillator 62 the field diode 51 is connected, and that the pump mode 30 modulation coil 61 is fed to the Polarides Cavity 1 with the screw 12 on a vorgesationsfeld with the frequency of 100 kHz to modugebene Frequency difference to the frequency of the covering. A low frequency signal from 20 Hz modulation mode will be voted on. The Pumppegcl lator 71 is led to the diode switch 51 to the is then with the frequency of 100 kHz amplitude amplitude of the pump energy with the frequency of denmodulated, and if the observation frequency 3s modulate 20 Hz. The Magnetic Polarisalnii corresponds to a resonance line, the energy field of which is adjusted so that the resonance of a level is coupled with another line, the particular line of the sample is observed, and the is irradiated with the pump source, the modula frequency of the pump mode and thus the frequency tion of the pumping source through the sample with the observer pumping excitation is through the rest of the Spekachteten Coupled resonance signal. The detected 40 trnms wobbled.

Resonance signal is ejected at the recorder 65 when the frequency of the pump excitation a

so that there is a spectrum. Energy level that corresponds to that provided by the

In the spectrometer according to Fi g. 4 the Isola observation channel is used to gate the observed resonance line 37 in the klystron arm of the observation frequency is coupled. is the 20 Hz modulation from the pump bridge 35 in addition, from the bimodal cavity reflective source 45 to the resonance signal of the observed line directed energy to prevent the frequency of the coupled through. More precisely, the 20 Hz modula klystrons 36 to pull along. In the same way hindering is caused by the output of the phase sensitive Isolators 48 and 47 microwave reflections chen detector 64 coupled through, and this is from the cavity 1 to it, the frequency of the Pumpkly amplified in the amplifier 72 and an input of a stronoszillators 46 pull along. 5 ° second phase-sensitive detector 73 assigned

In addition, the second isolator 47 is between the leads in which the 20 Hz resonance modulation is used

Diode switch 51 and the cavity 1 are provided, part of the 20 Hz modulation signal from the mo-

by any energy at the observation regulator 71 is compared to an output reso-

to be absorbed by the bimodal nance signal that is recorded in the recorder 65.

Cavity is coupled to the diode 51 and the 55 is drawn, depending on the

otherwise from there back into the cavity 1, the wobble of the pump frequency is reflected. The initial signa

would. If this signal reflected by the diode is the first derivative of the resonance signal of a ver

were present in the cavity, it would be for a simple spectrum of only such lines, between

Modulation of the observation resonance mode ensure that there is a coupling.

gene that would be detected as a resonance signal if 60 Sometimes it is desirable to use the absorption spec

working in pump mode. Trum to record instead of the first derivative de

A double electron resonance spectrometer of the absorption spectrum, and in this case there will be

in Fig. The type shown in FIG. 4 is particularly useful for the spectrometer according to FIG. 4 switched so that de

to observe the relaxation rates of certain 100 kHz oscillator its signal via switch 63 a

Electron groups within the sample to examine over- 65 to find overlapping spectra of Arte

lapping spectra of different paramagnetic in different physical environments ζ

different species in order to separate interactions from, for example, in different orientations

paramagnetic species to wrestle in different places with respect to the magnetic polarization fe

η diode switch 51 supplies, and the output of the obbel generator 66 via switch 68 with the Mor 69 is connected. The absorption spectrum recorded in field modulation is Particularly desirable for the analysis of anisotropic enlargements, such as those found in powders and glasses id large protein molecules are obtained.

10

Typically, spectra of the paramagnetic electronic resonance are a few 100 MHz wide, ur For observation of the electron-electron double resonance, both the pump and the beol lie Similar microwaves mode with the resonance i vY band and are frequency-wise around 1 to 500 MI separated.

For this purpose 3 sheets of drawings

Claims (2)

are, and with a device for introducing the sample to be examined in the first cavity claims: rich ("physical review" May 15, 1960, vol. 118, no. 4, pp. 939 to 945). 1. Bimodal cavity resonator for Spectro- 5 The object of the invention is to provide a bimodal gyromagnetic resonance meter, which makes a cavity resonator of this type available, has first cavity area in which two of the can be easily tuned without a Krtuzorthogonale Resonance modes can be excited, and coupling between the two resonance modes a facility for the introduction of the to uns, and in which the coupling of the retirees seekers Sample in the first cavity resonance modes is relatively uncritical to the cavity, rich, characterized in that around the production of such bimodal cavities the cavity resonator to a second cavity - without any special adjustment requirements area (3) in which only one of the two facilitate. Resonance modes of the first cavity region (2) According to the invention, this object can be excited and that the second cavity triggers that the cavity resonator has a second rich (3) with facilities (11) for voting Hohhaumbereich, in which only one of the two in it excitable resonance mode provide the resonance mode of the first cavity area is. is excitable, and that the second cavity region 2. Bimodal cavity resonator after an with devices for tuning the claim I in it, characterized in that the height! - 20 baren resonance mode is provided. In a derarraumresonator a third cavity area (4) term cavity resonator can have the tuning in which only the other of the two resonance modes can be excitable the resonance modes, and that the can be carried out without the other of the two third cavity area (4) is influenced by means of the resonance modes. According to one (12) for tuning the re-development of the invention that can be excited in it, the cavity resonance mode is provided. sonator a third cavity area in whichr