METHOD AND DEVICE FOR GENERATING A NUCLEAR MAGNETIC RESONANCE SPECTRUM OF NUCLEAR SPIN MOMENTS OF A SAMPLE

Abstract

The invention relates to a method for generating a nuclear magnetic resonance spectrum (4) of nuclear spin moments (6) of a sample (8), comprising a static magnetic field (B) permeating the sample (8), and a detection spin moment (16) with a detection region (18) surrounding the latter, said detection region extending at least partly into the sample (8), and also an antenna element (22) for radiating in frequency pulses (F) for influencing the nuclear spin moments (6) and radio-frequency pulses (H) for influencing the detection spin moment (16), wherein a polarization step (42) involves polarizing at least one portion of the nuclear spin moments (6) along the magnetic field (B) to form a longitudinal magnetization (M.sub.z), wherein a transfer step (44) involves converting the longitudinal magnetization (M.sub.z) into a transverse magnetization (M.sub.xy) by radiating in a frequency pulse (F) with a 90 flip angle, wherein a detection step (46) involves radiating in a sequence (S) of radio-frequency pulses (H) onto the detection spin moment (16) and subsequently detecting a signal (32) of the transverse magnetization (M.sub.xy) present in the detection region (18) and storing said signal as detection result (48) in a list (50), wherein the detection step is carried out a number of times repeatedly in succession, wherein the polarization step (42) and the transfer step (44) and also the detection steps (46) are carried out repeatedly until a predefined number of repetitions (N) is reached, wherein a new list (50) with detection results (48) is generated with each repetition (N), and wherein an evaluation step (54) involves jointly evaluating the detection results (48) of the lists (50) across all repetitions (N).

Claims

1. Method for generating a nuclear magnetic resonance spectrum (4) of nuclear spin moments (6) of a sample (8), comprising a static magnetic field (B) permeating the sample (8), and a detection spin moment (16) with a detection region (18) surrounding the latter, said detection region extending at least partly into the sample (8), and also an antenna element (22) for radiating in frequency pulses (F) for influencing the nuclear spin moments (6) and radio-frequency pulses (H) for influencing the detection spin moment (16), wherein a polarization step (42) involves polarizing at least one portion of the nuclear spin moments (6) along the magnetic field (B) to form a longitudinal magnetization (M.sub.z), wherein a transfer step (44) involves converting the longitudinal magnetization (M.sub.z) into a transverse magnetization (M.sub.xy) by radiating in a frequency pulse (F) with a 90 flip angle, wherein a detection step (46) involves radiating in a sequence (S) of radio-frequency pulses (H) onto the detection spin moment (16) and subsequently detecting a signal (32) of the transverse magnetization (M.sub.xy) present in the detection region (18) and storing said signal as detection result (48) in a list (50), wherein the detection step is carried out a number of times repeatedly in succession, wherein the polarization step (42) and the transfer step (44) and also the detection steps (46) are carried out repeatedly until a predefined number of repetitions (N) is reached, wherein a new list (50) with detection results (48) is generated with each repetition (N), and wherein an evaluation step (54) involves jointly evaluating the detection results (48) of the lists (50) across all repetitions (N).

2. Method according to claim 1, characterized in that the detection spin moment (16) is formed by an electron spin moment of a colour centre of a solid (12) in contact with the sample (8), in particular of a nitrogen-vacancy centre of a diamond.

3. Method according to claim 1 or 2, characterized in that the nuclear spin moments (16) are hyperpolarized in the polarization step (42) in order to form the longitudinal magnetization (M.sub.z).

4. Method according to claim 3, characterized in that the nuclear spin moments (16) are hydropolarized with polarization spin moments (17) of the solid (12).

5. Method according to any of claims 1 to 4, characterized in that the sequence (S) is generated as a decoupling sequence for the detection spin moment (16), wherein the sequence (S) comprises a radio-frequency pulse (H.sub.Y.sup.90) with 90 flip angle along a first pulse axis (Y) and a radio-frequency pulse (H.sub.X.sup.90) with 90 flip angle along a second pulse axis (X), oriented perpendicularly to the first pulse axis (Y), and also, arranged therebetween, a number of radio-frequency pulses (H.sub.X.sup.180, H.sub.Y.sup.180, H.sub.X.sup.180, H.sub.Y.sup.180) with 180 flip angle along two pulse axes (X, Y) oriented perpendicularly to one another, and wherein the pulse spacing between the radio-frequency pulses (H.sub.X.sup.180, H.sub.Y.sup.180, H.sub.X.sup.180, H.sub.Y.sup.180) is adapted to a precession frequency of the nuclear spin moments (6) in the magnetic field (B).

6. Method according to any of claims 1 to 5, characterized in that the evaluation step (54) involves summing or averaging the detection results (48) of the lists (50) across the repetitions point-by-point to form detection results (48) of a resulting result list (68).

7. Method according to claim 6, characterized in that the evaluation step (54) involves autocorrelating and then Fourier-transforming the detection results (48) of the result list (68).

8. Method according to claim 6, characterized in that the evaluation step (54) involves evaluating the detection results (48) of the result list (68) by means of a Bayesian inference.

9. Method according to any of claims 1 to 8, characterized in that the detection steps (46) are carried out simultaneously on a plurality of detection spin moments (16).

10. Device (2) for generating a nuclear magnetic resonance spectrum (4) of nuclear spin moments (6) of a sample (8), comprising a magnet (10) for generating a static magnetic field (B) and a solid (12) with at least one integrated detection spin moment (16) and also an antenna element (22) and a controller (28) for carrying out a method according to any of claims 1 to 9.

11. Device (2) according to claim 10, characterized in that the or each detection spin moment (16) is arranged in the region of a nanostructuring (19), in particular a nanoslit, said nanostructuring being introduced into the solid (12).

Description

[0059] Exemplary embodiments of the invention are explained in greater detail below with reference to a drawing, in which in simplified and schematic illustrations:

[0060] FIG. 1 shows a device for generating a nuclear magnetic resonance spectrum of nuclear spin moments of a sample,

[0061] FIG. 2a shows a detection spin moment with a detection region permeating the sample in an unpolarized state of the sample,

[0062] FIG. 2b shows the detection spin moment with the detection region in a fully polarized state of the sample,

[0063] FIG. 3 shows a flow diagram of a method for generating a nuclear magnetic resonance spectrum of nuclear spin moments of a sample,

[0064] FIG. 4 shows a measurement protocol according to the method,

[0065] FIG. 5 shows an averaged nuclear magnetic resonance signal for different numbers of repetitions of the measurement protocol,

[0066] FIG. 6 shows an averaged photon detection for different numbers of repetitions of the measurement protocol,

[0067] FIG. 7 shows an averaged nuclear magnetic resonance signal for 100 repetitions,

[0068] FIG. 8 shows a nuclear magnetic resonance spectrum of the nuclear magnetic resonance signal according to FIG. 7, and

[0069] FIG. 9 shows a diamond with a nanostructuring and a number of detection spin moments and polarizaiton spin moments.

[0070] Mutually corresponding parts and variables are always provided with the same reference signs in all the figures.

[0071] The device 2 illustrated in FIG. 1 is suitable and configured for generating a nuclear magnetic resonance spectrum 4 (FIG. 8) of nuclear spin moments 6 (FIG. 2a, FIG. 2b) of a sample 8. The device 2 comprises a magnet 10, having a north pole 10a and a south pole 10b, between which a homogeneous magnetic field B is generated during operation. During operation, the sample 8 together with a solid 12 is positioned for example in a region of the magnet 10 that is freed between the north pole 10a and south pole 10b.

[0072] The sample 8 is a liquid material sample, for example, which is applied on the surface 14 of the solid 12. As illustrated schematically and in a simplified manner in FIG. 2a and FIG. 2b, the sample 8 has a number of nuclear spin moments 6. The nuclear spin moments 6 are provided with reference signs merely by way of example in FIGS. 2a and 2b. The solid 12 has near the surface 14 at least one detection spin moment 16 and at least one polarization spin moment 17. The detection spin moment 16 has a detection region 18, which extends into the sample 8.

[0073] The solid 12 is embodied as a diamond with a number of nanoslits, which are shown merely by way of example in FIG. 9 and which are introduced as nanostructuring 19 into the surface 14 of the solid 12. The detection spin moments 16 and polarization spin moments 17 here are preferably embodied in each case as an electron spin moment of a colour centre, in particular of an NV centre. The detection spin moment 16 and the polarization spin moment 17 are polarizable with a laser light 20 of a laser (not shown) along a polarization axis, which is oriented for example parallel to the magnetic field B in FIGS. 2a and 2b.

[0074] In this case, the solid 12 substantially comprises two layers 21a, 21b, in each of which a number of NV centres are arranged (FIG. 9). The layers 21a, 21b in this case are at different distances from the surface 14 of the diamond 12.

[0075] The layer 21a, also referred to hereinafter as polarization layer, is at a small distance from the surface 14, in particular approximately 20 nm. A number of NV centres are arranged in the polarization layer 21a, the electron spin moments of which NV centres are used as polarization spin moments 17 for the hyperpolarization of the nuclear spin moments 6 of the sample 8.

[0076] Those NV centres whose electron spin moments act as detection spin moments 16 are arranged in the layer 21b arranged at a distance from the polarization layer 21a. In this case, the layer 21b, also referred to hereinafter as detection layer, is at a distance for example of approximately 1 m from the surface 14.

[0077] For exciting and influencing the nuclear spin moments 6 of the sample 8 and also the detection spin moments 16 and polarization spin moments 17 of the solid 12, the device 2 comprises an antenna element 22. The antenna element 22 is coupled to a signal generator 24. During operation, the signal generator 24 is suitable and configured to generate frequency pulses F and radio-frequency pulses H (FIG. 4) having a specific frequency, pulse duration, pulse amplitude and pulse phase angle. The generated frequency pulses F and radio-frequency pulses H are radiated onto the sample 8 and the solid 12 by means of the antenna element 22.

[0078] In this case, the frequency pulses F suitably have a signal frequency that corresponds to a Larmor frequency of the nuclear spin moments 6 in the magnetic field B. In this case, the frequency pulses F have for example a signal frequency in the radio-frequency range, in particular in a kHz to MHz range. The radio-frequency pulses H correspondingly suitably have a signal frequency corresponding to the Larmor frequency of the detection spin moment 16 and of the polarization spin moments 17, respectively, such that a resonant, in particular coherent, manipulation and influencing of the detection spin moment 16 is brought about. In this case, the signal frequency of the radio-frequency pulses H is preferably in the microwave range, in particular in an MHz to GHz range. In this case, the Larmor frequencies of the nuclear spin moments 6 and of the detection spin moment 16 are suitably different from one another, such that upon an irradiation the frequency pulses F have an influencing effect only on the nuclear spin moments 6 of the sample 8 and the radio-frequency pulses H have an influencing effect only on the detection spin moment 16.

[0079] The device 2 comprises a sensor element 26, in particular an avalanche photodiode, which is connected in terms of signalling to a controller 28. The controller 28 and the signal generator 24 are coupled to a local oscillator 30, for example a quartz crystal. The oscillator 30 generates a clock frequency f.sub.LO, by means of which the controller 28 and/or the signal generator 24 are operated jointly in a synchronized manner.

[0080] The solid 12 and the sample 8 are shown schematically and in a simplified manner in FIG. 2a. In this case, the nuclear spin moments 6 are for example part of a respective molecule that diffuses (molecularly) in the sample 8. The detection spin moment 16 is arranged near the surface 14, in particular less than 1 m below the surface 14, within the detection layer 21b. The polarization layer 21a having the polarization spin moments 17 suitable for hyperpolarization is not shown in FIGS. 2a and 2b.

[0081] The nuclear spin moments 6 have in the detection region 18 a statistical magnetization M.sub.stat, that is to say a random net alignment of the nuclear spin moments 6. The magnetization M.sub.stat undergoes Larmor precession about the magnetic field B and thus generates an alternating magnetic field as (nuclear magnetic resonance) signal 32, which is detectable by means of the detection spin moment 16.

[0082] The magnetization M.sub.stat has a random (net) phase in this case on account of the substantially randomly oriented nuclear spin moments 6. On account of the molecular diffusion, which is illustrated by way of example with curved arrows in the figures, during a correlation time nuclear spin moments 6 diffuse out of and/or into the detection region 18. As a result, the amplitude and phase of the magnetization M.sub.stat are changed randomly, as a result of which the signal 32 is influenced. This makes it more difficult to generate a nuclear magnetic resonance spectrum with high spectral resolution.

[0083] FIG. 3 shows a method for generating the nuclear magnetic resonance spectrum 4.

[0084] The method is started in a first method step 34 and, in a subsequent method step 36, a count n is set to zero. Afterwards, a measurement sequence 38 is started.

[0085] In a method step 40 of the measurement sequence 38, the count n is increased by one. A subsequent polarization step 42 involves polarizing at least one portion of the nuclear spin moments 6 of the sample 8 along the magnetic field B to form a longitudinal magnetization M.sub.z. In this case, the nuclear spin moments 6 are preferably hyperpolarized, such that for example at least 0.1%, in particular at least 1%, of the nuclear spin moments 6 of the sample 8 are oriented in an identical way.

[0086] In the polarization step 42, the NV centres of the polarization layer 21a are optically polarized with the laser light 20; that is to say that the electron or polarization spin moments 17 thereof are prepared into a defined (spin) state. The resulting polarizaiton of the polarization spin moments 17 is transferred from the polarization spin moments 17 to the nuclear spin moments 6 by means of a polarization sequence (not shown in more specific detail) by irradiation with a number of radio-frequency pulses H. The substeps of the optical polarization and the subsequent polarization transfer are carried out in a manner repeated a number of times, for example, in order to bring about a higher polarization of the nuclear spin moments 6.

[0087] A subsequent transfer step 44 of the method involves converting the longitudinal magnetization M.sub.z generated in the polarization step 42 into a transverse magnetization M.sub.xy by radiating in a frequency pulse F with a 90 flip angle.

[0088] A detection step 46 of the method involves radiating in a sequence S (FIG. 4) of radio-frequency pulses H onto the detection spin moment 16 and subsequently detecting a signal 32 of the transverse magnetization M.sub.xy present in the detection region. The detected signal 32 is detected by means of the sensor element 26 and stored as a detection result 48 in a list 50 in a memory of the controller 28. In this case, the detection step 46 is carried out a number of times repeatedly in succession, such that the list 50 is progressively filled with successive detection results 48. By way of example, just one detection step 46 is illustrated in FIG. 3.

[0089] The effect of the polarization step 42 and of the transfer step 44 is shown for a 100% polarization of the nuclear spin moments 6 in FIG. 2b. Generating the longitudinal magnetization M.sub.z and converting it into the transverse magnetization M.sub.xy ensures that substantially no influencing of the phase and/or of the amplitude of the transverse magnetization M.sub.xy is effected even in the case of a diffusion of the nuclear spin moments 6. In other words, the detectable signal 32 is substantially not influenced by the diffusion within the sample 8.

[0090] At the end of the measurement sequence 38, the count n is compared with a predefined or predefinable number of repetitions N in a comparison 52. In the case of a negative comparison result, in which the count n is less than the desired number of repetitions N, the measurement sequence 38 is carried out repeatedly, wherein at the beginning of the measurement sequence 38 a new list 50 is generated for the new detection results 48.

[0091] In the case of a positive comparison result of the comparison 52, in which the count n is equal to the desired number of sequential repetitions N, the measurement sequence 38 is ended and an evaluation step 54 of the method is started. The evaluation step 54 involves jointly evaluating the detection results 48 of the lists 50 across all repetitions N and generating the nuclear magnetic resonance spectrum 4. Finally, the method is ended with a method step 56.

[0092] The measurement sequence 38 is explained in greater detail below with reference to FIG. 4. The polarization step 42 is not illustrated in FIG. 4. The illustration in FIG. 4 has substantially three sections 58, 60, 62. In sections 58 and 62, frequency pulses F and radio-frequency pulses H are illustrated in a blocklike manner, wherein the pulses F, H hereinafter are provided with a subscripted index for describing a pulse axis X, Y and with a superscripted index for describing the respective flip angle (90, 180).

[0093] Section 62 substantially illustrates the transfer step 44. In this exemplary embodiment, the longitudinal magnetization M.sub.z is converted into the transverse magnetization M.sub.xy by means of a frequency pulse F.sub.Y.sup.90, that is to say a frequency pulse F with 90 flip angle along the Y-pulse axis. In this case, the transverse magnetization M.sub.xy decays during a relaxation time T. This means that the signal 32 is substantially a damped oscillation having an oscillation frequency equal to the Larmor frequency of the transverse magnetization M.sub.xy, wherein the decay constant or decay time is equal to the relaxation time T. In this case, the relaxation time T is in particular equal to a transverse relaxation time of the nuclear spin moments 6 in the sample 8, for example equal to a T.sub.2* or T.sub.2 relaxation.

[0094] The detection steps 46 carried out repeatedly are shown schematically and in a simplified manner in section 60. The detection steps 46 in this case substantially comprise the sequence S and also a read-out step 64. In the read-out step 64, the sensor element 26 generates the detection results 48. Preferably, the detection steps 46 are in this case carried out repeatedly during the relaxation time T, such that substantially the complete signal decay of the signal 32 is detected.

[0095] Section 58 shows one exemplary embodiment of the sequences S. In this case, the sequence S is embodied as a decoupling sequence, in particular an XY-decoupling sequence. In the exemplary embodiment in FIG. 4, the sequence S is embodied in particular as an XY4-sequence. In this configuration, the sequence S comprises as initial pulse a radio-frequency pulse H.sub.Y.sup.90, by means of which the detection spin moment 16 is put into a (transverse) superposition state. In this state, the detection spin moment 16 precesses at its Larmor frequency about the magnetic field B, wherein the signal 32 influences the detection spin moment 16 on account of dipolar interactions.

[0096] In order to improve the sensitivity of the detection spin moment 16 to the signal 32, the sequence S comprises four successive radio-frequency pulses H.sub.X.sup.180, H.sub.Y.sup.180, H.sub.X.sup.180 and H.sub.Y.sup.180. The radio-frequency pulses H.sub.X.sup.180, H.sub.Y.sup.180, H.sub.X.sup.180, H.sub.Y.sup.180 are spaced apart equidistantly from one another and each bring about a refocusing of the temporal development of the detection spin moment 16, as a result of which the radio-frequency pulses H.sub.X.sup.180, H.sub.Y.sup.180, H.sub.X.sup.180, H.sub.Y.sup.180 act as an effective frequency filter for the detection spin moment 16. In this case, the pulse spacings between the radio-frequency pulses H.sub.X.sup.180, H.sub.Y.sup.180, H.sub.X.sup.180, H.sub.Y.sup.180 are in particular equal to half a Larmor period of the precessing transverse magnetization M.sub.xy, as a result of which the phase brought about by the signal 32 between the radio-frequency pulses H.sub.X.sup.180, H.sub.Y.sup.180, H.sub.X.sup.180, H.sub.Y.sup.180 is effectively summed across the sequence S.

[0097] The sequence S comprises at the end an end pulse in the form of a radio-frequency pulse H.sub.X.sup.90. The radio-frequency pulse H.sub.X.sup.90 converts the superposition state of the detection spin moment 16 at the end of the sequence S into a population state of the spin or energy levels of the detection spin moment 16. In this case, the phase brought about by the signal 32 is converted into a corresponding population difference of said energy levels, which is detected by means of the read-out step 64.

[0098] The detection spin moment 16 is, in particular, an electron spin moment of an NV centre. In the read-out step 64, the detection spin moment 16 is irradiated with the, in particular green, laser light 20. As a result, depending on the population state at the end of the sequence S the detection spin moment 16 on the one hand emits photons 66 in the red wavelength range. On the other hand, the state of the detection spin moment 16 is thereby optically polarized, that is to say put into an initial state, such that the subsequent detection step 46 can be started directly thereafter. The emitted photons 66 are detected by the sensor element 26, wherein a corresponding photon number or photon counting rate is stored as detection result 48 in the respective list 50.

[0099] By virtue of the clock frequency f.sub.LO of the oscillator and the controller 28 and signal generator 24 synchronized therewith, the individual method steps 40, 42, 44 and 52 of the measurement sequence 38 are carried out in a manner synchronized with one another. As a result, the signal 32 is always measurable reproducibly during successive repetitions. In particular, the repeatedly performed detection steps 46 substantially correspond to discrete time steps at which the temporal development of the signal 32 is detected. In this case, the detection results 48 are synchronized upon storage in the respective list 50, that is to say are provided with an additional time value, for example.

[0100] The lists 50 of the repetitions N of the measurement sequence 38 are evaluated jointly in the evaluation step 54. The evaluation step 54 is explained in greater detail below on the basis of the exemplary embodiments in FIGS. 5 to 8. The exemplary embodiments in FIG. 5 and FIG. 6 show the signal profiles in which approximately 0.1% of the nuclear spin moments 6 is polarized in the polarization step 42. FIGS. 7 and 8 show exemplary embodiments in the case of a 1% polarization of the nuclear spin moments 6.

[0101] The evaluation step 54 involves summing the detection results 48 of the lists 50 across the repetitions N point-by-point to form a resulting result list 68. The entries or summed detection results 48 of the result list 68 are subsequently autocorrelated.

[0102] FIG. 6 has three sections 70, 72, 74. The sections 70, 72, 74 in each case show the entries of the result list 68 for different numbers of repetitions N. A time t resulting from the synchronization of the oscillator 30 is plotted along the respective x-axis or abscissa axis. The respective photon number P is shown along the y-axis or ordinate axis. The summed detection results 48 of the respective result list 68 are represented as dots.

[0103] FIG. 5 shows, in three sections 76, 78 and 80, the autocorrelated signal data of the corresponding result lists 68 in the sections 70, 72 and 74. In this case, the autocorrelated signal data substantially correspond to the signal 32 of the transverse magnetization M.sub.xy. Time t is plotted along the respective x-axis or abscissa axis. The respective signal amplitude A is shown along the y-axis or ordinate axis.

[0104] The section 70 shows the detection results 48 of a result list 68 for a single repetition N of the measurement sequence 38, that is to say that N=1. The correspondingly autocorrelated signal data of the detection results 48 are illustrated in the section 76. On account of a limited collector efficiency of the sensor element 26, photons 66 are only occasionally detected during the read-out step 64 of the detection steps 46. The autocorrelated signal of the section 76 has a correspondingly poor signal-to-noise ratio.

[0105] The polarization step 42 and the transfer step 44 ensure that the transverse magnetization M.sub.xy always has the same initial phase during the measurement sequence 38. As a result, the same signal 32 is always measured during the sequential repetitions N; this means that the detection results 48 of the lists 50 are detected at identical times of the temporal development of the signal 32. As the number of repetitions N increases, the point-by-point summing of the detection results 48 to form the detection results 48 thus brings about an improved signal-to-noise ratio. By way of example, sections 72 and 78 show the results of a result list 68 for one hundred repetitions N (N=100) and sections 74 and 80 show the results of a result list 68 for three hundred repetitions N (N=300). The predefined number of repetitions N thus determines the resulting signal quality.

[0106] In the evaluation step 54, the autocorrelated data of the result list 68 are Fourier-transformed. In this case, the absolute value of the Fourier-transformed data forms the nuclear magnetic resonance spectrum 4 generated.

[0107] FIG. 7 shows the autocorrelated signal data of a result list 68 for a 1% polarization of the nuclear spin moments 6 and one hundred repetitions N (N=100) of the measurement sequence 38 for the entire relaxation time T. Time t is shown along the x-axis or abscissa axis and the signal amplitude A is shown along the y-axis or ordinate axis.

[0108] FIG. 8 shows the datagenerated by means of a fast Fourier transformation (FFT)of the autocorrelated signal data of the result list 68 in accordance with FIG. 7. The frequency f is shown along the x-axis or abscissa axis and the signal amplitude A of the nuclear magnetic resonance spectrum 4 generated is shown along the y-axis or ordinate axis.

[0109] The invention is not restricted to the exemplary embodiments described above. Rather, other variants of the invention can also be derived therefrom by the person skilled in the art, without departing from the subject matter of the invention. In particular, all individual features described in association with the exemplary embodiments are furthermore also able to be combined with one another in a different way, without departing from the subject matter of the invention.

[0110] In this regard, it is conceivable, for example, to carry out the detection steps 46 simultaneously or in parallel on a plurality of detection spin moments 16, for example in the course of a common widefield detection.

[0111] Furthermore, it is possible for the detection results 48 of the result list 68 to be evaluated by means of Bayesian inference in the evaluation step 54 for the generation of the nuclear magnetic resonance spectrum 4.

LIST OF REFERENCE SIGNS

[0112] 2 Device [0113] 4 Nuclear magnetic resonance spectrum [0114] 6 Nuclear spin moment [0115] 8 Sample [0116] 10 Magnet [0117] 10a North pole [0118] 10b South pole [0119] 12 Solid/diamond [0120] 14 Surface [0121] 16 Detection spin moment [0122] 17 Polarization spin moment [0123] 18 Detection region [0124] 19 Nanostructuring [0125] 20 Laser light [0126] 21a Layer/polarization layer [0127] 21b Layer/detection layer [0128] 22 Antenna element [0129] 24 Signal generator [0130] 26 Sensor element [0131] 28 Controller [0132] 30 Oscillator [0133] 32, 32 Signal [0134] 34,36 Method step [0135] 38 Measurement sequence [0136] 40 Method step [0137] 42 Polarization step [0138] 44 Transfer step [0139] 46 Detection step [0140] 48, 48 Detection result [0141] 50 List [0142] 52 Comparison [0143] 54 Evaluation step [0144] 56 Method step [0145] 58, 60, 62 Section [0146] 64 Read-out step [0147] 66 Photon [0148] 68 Result list [0149] 70, 72, 74 Section [0150] 76, 78, 80 Section [0151] B Magnetic field [0152] F Frequency pulse [0153] H Radio-frequency pulse [0154] f.sub.LO Clock frequency [0155] M.sub.stat Magnetization [0156] n Count [0157] M.sub.z Longitudinal magnetization [0158] M.sub.xy Transverse magnetization [0159] S Sequence [0160] X, Y Pulse axis [0161] N Repetition [0162] T Relaxation time [0163] A, A Signal amplitude [0164] t Time [0165] P Photon number [0166] f Frequency