JP6671745B2 - Near-field probe structure and scanning probe microscope - Google Patents

Description

  The present invention relates to a near-field probe structure and a scanning probe microscope.

  By adding a photodetection magnetic resonance sensor using nanodiamond particles and diamond rods containing a nitrogen-vacancy complex center (NV center) to the probe tip of a scanning probe microscope, nanoscale magnetic materials and Detection of a stray magnetic field from a paramagnetic single electron spin has been attempted (see Non-Patent Documents 1 and 2).

  In connection with a photodetection magnetic resonance sensor using nanodiamond particles, a technique has been proposed in which nanodiamond particles are incorporated into cells and measured (see Patent Document 1).

  A near-field probe using an optical fiber has been proposed (see Patent Document 2).

  Conventionally, in sensors using nanodiamond particles or diamond rods containing an NV center, excitation light is applied to the NV center via an objective lens, and fluorescence from the NV center is collected and detected via the objective lens. Light irradiation detection technology by the far field method is used.

  However, such a technique has a problem that, for example, the light collection efficiency of the objective lens is low (the upper limit value of NA is about 1.45) in fluorescence detection, so that less than 1% of total fluorescence can be detected. ing.

JP 2011-180570 A U.S. Pat. No. 5,559,330

G. Barasbramanian et al., Nature, October 2008, Vol. 648-651 Grinolds et al., Nature Physics, February 2013, Volume 9, pp. 215-219

  An object of the present invention is to provide a near-field probe structure capable of improving the efficiency of detecting fluorescence from the center of an NV, and a scanning probe microscope using the same.

  It is another object of the present invention to provide a near-field probe structure having a novel structure and a scanning probe microscope using the same.

According to one aspect of the invention,
A diamond member containing a nitrogen-vacancy composite center;
The diamond member so that the center of the nitrogen-vacancy complex is irradiated with excitation light under a near field, and the excitation light can extract fluorescence generated under the near field from the center of the nitrogen-vacancy complex. A light irradiation extraction member fixedly arranged with respect to,
Is provided.

According to another aspect of the present invention,
A probe mechanism used to observe the sample,
A scanning mechanism for controlling a relative position between the sample and the probe mechanism,
Has,
The probe mechanism,
A diamond member containing a nitrogen-vacancy composite center;
The diamond member so that the center of the nitrogen-vacancy complex is irradiated with excitation light under a near field, and the excitation light can extract fluorescence generated under the near field from the center of the nitrogen-vacancy complex. A light irradiation extraction member fixedly arranged with respect to,
A scanning probe microscope having a near-field probe structure having the following is provided.

  As an example of the effect, since the fluorescence generated under the near field can be extracted from the center of the nitrogen-vacancy complex by the light irradiation extraction member, the fluorescence from the center of the nitrogen-vacancy complex is condensed by the objective lens. As compared with the technique of detecting the fluorescence, the efficiency of detecting the fluorescence can be improved.

FIG. 1 is a schematic diagram showing an overall configuration example of an AFM according to the first embodiment (or the second embodiment) of the present invention. FIG. 2 is a schematic diagram illustrating a configuration example of the near-field probe structure according to the first embodiment. FIG. 3A is a schematic diagram illustrating a configuration example of a near-field probe structure according to the second embodiment, and FIG. 3B is a configuration of a connection portion between the near-field probe structure and an optical fiber according to the second embodiment. It is a schematic diagram showing an example. FIGS. 4A to 4D are schematic perspective views of a base material forming a diamond rod having a near-field probe structure according to the second embodiment. FIG. 5A is a schematic perspective view of a base material forming a diamond rod having a near-field probe structure according to the second embodiment, and FIGS. 5B to 5D illustrate diamonds according to the second embodiment. It is the schematic sectional drawing seen from the side of the rod.

  A scanning probe microscope (SPM) according to an embodiment of the present invention will be described. The scanning probe microscope according to the embodiment has a near-field probe structure using a diamond member containing a nitrogen-vacancy complex center (NV center), as described below.

  Here, a description will be given by taking a frequency modulation atomic force microscope (FM-AFM) as an example of the scanning probe microscope. The exemplary FM-AFM may be hereinafter simply referred to as an AFM.

  First, a first embodiment will be described with reference to FIGS. FIG. 1 is a schematic diagram illustrating an overall configuration example of the AFM 10 according to the first embodiment. FIG. 2 is a schematic diagram illustrating a configuration example of the near-field probe structure 120 of the AFM 10 according to the first embodiment (the near-field probe structure 120 according to the first embodiment).

  The AFM 10 has a probe mechanism 100 used for observing the sample 20, and a scanning mechanism 200 for controlling a relative position between the sample 20 and the probe mechanism 100.

  The probe mechanism 100 has a quartz oscillator 110 and a near-field probe structure 120 attached to the tip of the quartz oscillator 110. Crystal oscillator 110 oscillates at a predetermined frequency by an AC voltage applied from AC voltage source 111. As the crystal unit 110, for example, a tuning-fork type crystal unit is used. In this case, the near-field probe structure 120 is attached to the tip of the lower leg (on the side of the sample 20) of the crystal unit 110.

  The tip of the near-field probe structure 120 is used as a probe facing the sample 20. In the near-field probe structure 120, the side facing the sample 20 is referred to as the tip side, and the opposite side is referred to as the root side.

  In the near-field probe structure 120 according to the first embodiment, as shown in an enlarged manner in FIG. 2, nano diamond particles 130 as a diamond member containing an NV center 131 are provided at the tip of an optical fiber probe 140 as a light irradiation extraction member. A structure attached to the part is used. For the sake of illustration, FIG. 2 shows that the nanodiamond particles 130 are attached to the tip of the optical fiber probe 140 at a position slightly shifted to the side surface. It is more preferable that the nano diamond particles 130 are attached to the (bottom surface).

  The optical fiber probe (light irradiation / extraction member in the first embodiment) 140 is an optical fiber having a tip portion whose diameter is smaller than the wavelength of excitation light 311 described later, and includes nano diamond particles (diamond member in the first embodiment) 130. Is fixed to the nano diamond particles 130 so that the NV center 131 contained in the Nb is irradiated with the excitation light 311 under the near field, and the excitation light 311 can extract the fluorescence 321 generated under the near field from the NV center 131. (In a fixed positional relationship).

  As the optical fiber probe 140, for example, a commercially available optical fiber probe can be used. For example, a probe whose outer surface is coated with a transparent conductive film 142 made of indium tin oxide (ITO) can be used. Since the conductive film 142 is formed on the outer surface of the near-field probe structure 120, the near-field probe structure 120 can be used in a probe mechanism of a scanning tunneling microscope (STM).

  The diameter (diameter) of the tip of the core 141 of the optical fiber probe 140 is preferably 100 nm or less. The diameter of the nano diamond particles 130 is preferably 100 nm or less, more preferably 50 nm or less, for example, 20 nm to 40 nm. Here, the “diameter of the nanodiamond particles 130” is represented by the diameter of the smallest one of the spheres that can surround (enclose) the nanodiamond particles 130.

  The NV center 131 contained in the nano diamond particles 130 is used as a sensor as described later. Even if the nano diamond particle 130 contains a plurality of NV centers 131, it can be used as a sensor. However, in order to optimize the spatial resolution of the sensor, the nano diamond particle 130 contains a single NV center 131. It is preferred that That is, from the viewpoint of spatial resolution, it is most preferable to use a single NV center 131 as a sensor.

  In order to stabilize the behavior as a sensor, the NV center 131 is located within a range of 3 nm to 10 nm as a height (depth) from the end on the tip side of the nano diamond particle 130 (for example, about 5 nm). Is preferable.)

  The base side of the optical fiber probe 140 is connected to the light irradiation detection device 300 via the optical fiber 301. The light irradiation detection device 300 includes an excitation laser light source 310, a fluorescence detector 320, and a branch optical system 330. Note that the optical fiber 301 may be regarded as a part of the light irradiation detection device 300. Further, the light irradiation detection device 300 may be regarded as a part of the AFM 10.

  The excitation laser light source 310 emits, for example, green laser light having a wavelength of 532 nm as the excitation light 311. Excitation light 311 emitted from the excitation laser light source 310 enters the optical fiber probe 140 via the branch optical system 330 and the optical fiber 301.

  The excitation light 311 incident on the optical fiber probe 140 irradiates the NV center 131 under the near field. The excitation light 311 emits red light having a wavelength of 600 nm to 800 nm as fluorescence 321 from the NV center 131 under a near field. The fluorescent light 321 generated from the NV center 131 under the near field is taken out by the optical fiber probe 140 and enters the fluorescent light detector 320 via the optical fiber 301 and the branch optical system 330.

  The branching optical system 330 selectively propagates the excitation light 311 from the excitation laser light source 310 to the near-field probe structure 120 and selectively emits the fluorescence 321 from the near-field probe structure 120 to the fluorescence detector 320. To be propagated. The branch optical system 330 is configured using, for example, a dichroic mirror, a filter, and the like.

  The fluorescence detector 320 detects the intensity of the fluorescence 321 and the like. The fluorescence detector 320 is configured using, for example, an avalanche photodiode.

  The intensity of the fluorescence 321 is measured while irradiating the NV center 131 with a microwave. At this time, the intensity of the fluorescent light 321 changes depending on the frequency of the irradiation microwave. In a surrounding environment, for example, in a state not affected by a magnetic field or the like, a dip is observed in the intensity spectrum of the fluorescence 321 at 2.87 GHz at which an electron spin resonance (ESR) transition occurs at the NV center 131.

  The shape of the intensity spectrum of the fluorescent light 321 with respect to the frequency of the irradiating microwave (hereinafter sometimes simply referred to as the fluorescent light intensity spectrum) changes under the influence of the surrounding environment, for example, a magnetic field. That is, the fluorescence intensity spectrum of the NV center 131 arranged at the tip of the near-field probe structure 120 changes its shape due to the magnetic field or the like caused by the electron spin 21 and the nuclear spin 22 contained in the sample 20. That is, the NV center 131 disposed at the tip of the near-field probe structure 120 can be used as a sensor that detects the state of the sample 20 via the fluorescence intensity spectrum.

  For example, due to Zeeman splitting caused by the magnetic field of the sample 20, two dips are observed in the fluorescence intensity spectrum of the NV center 131. Further, the frequency difference between the dips changes depending on the magnitude of the magnetic field. Thus, the NV center 131 can be used as a magnetic field sensor.

  Further, for example, the frequency at which a dip in the fluorescence intensity spectrum is generated is shifted depending on the temperature of the sample 20. Also, for example, depending on the electric field of the sample 20, the shape of the fluorescence intensity spectrum shows a change similar to that of the magnetic field. As described above, the NV center 131 can be used as a temperature sensor or an electric field sensor.

  The method of irradiating the NV center 131 with microwaves to acquire a fluorescence intensity spectrum is not particularly limited. In this example, a wire 24 for emitting a microwave 23 is mounted on the surface of the sample 20, and the wire 24 is connected to a microwave source 400 outside the sample 20. As the wire 24, for example, a copper wire having a diameter of about 30 μm is used. Note that the microwave source 400 may be regarded as a part of the AFM 10.

  The magnetic field application device 500 applies, for example, a static magnetic field 501 in the Z direction. By adopting a device configuration capable of applying the static magnetic field 501 by the magnetic field application device 500, measurement conditions can be changed in various ways, and the degree of freedom of measurement can be increased. Note that the magnetic field applying device 500 may be regarded as a part of the AFM 10.

  The spin direction of the NV center 131 is preferably parallel to the direction of the static magnetic field 501 applied from the magnetic field application device 500, that is, for example, parallel to the Z direction in order to maximize the effect of Zeeman splitting. .

  In order to make the spin of the NV center 131 parallel to the Z direction, it is preferable that the spin of the NV center 131 be parallel to the extending direction of the tip of the optical fiber probe 140. That is, it is preferable that the nano diamond particles 130 are attached to the optical fiber probe 140 such that the spin of the NV center 131 is parallel to the extending direction of the tip of the optical fiber probe 140.

  The scanning mechanism 200 has a fine movement piezo stage 210 and a control device 220. The sample 20 is placed on the fine movement piezo stage 210. The fine piezo stage 210 is mounted on a coarse piezo stage 230, and the coarse piezo stage 230 is mounted on a vibration isolation table 600.

  The coarse piezo stage 230 has a movable range of, for example, about 5 mm in each of the X direction, the Y direction, and the Z direction (height direction), and is used for rough positioning of the sample 20. The fine movement piezo stage 210 has a movable range of, for example, about 100 μm in each of the X direction, the Y direction, and the Z direction (height direction), and allows precise positioning of the sample 20 and continuous observation position in the XY plane. Used for dynamic scanning. Note that the coarse piezo stage 230 may be regarded as a part of the scanning mechanism 200.

  The control device 220 controls the coarse piezo stage 230 and the fine piezo stage 210 to control the position of the sample 20. Further, the control device 220 changes the vibration frequency of the crystal unit 110 due to a change in the positional relationship between the probe mechanism 100 and the sample 20 in the Z direction (height direction) during continuous scanning in the XY plane. Is detected, and the fine-movement piezo stage 210 is feedback-controlled in the Z direction so that the height of the sample 20 at which the oscillation frequency of the crystal unit 110 is constant is maintained.

  Next, an example of a method for manufacturing the near-field probe structure 120 according to the first embodiment will be described. A plurality of candidate nanodiamond particles to be attached to the near-field probe structure 120 prepare a material dispersed on a supporting substrate. For each nanodiamond particle of this material, a fluorescence intensity spectrum is measured, observation is performed by a confocal microscope, and observation of an anti-bunching signal is performed by a photon correlation method to contain a single NV center 131. The nano diamond particles 130 which are located at the depth of 3 nm to 10 nm as described above and whose spin at the NV center 131 is parallel to the Z direction are selected. The selected nano diamond particles 130 are attached to the tip of the optical fiber probe 140 by, for example, an adhesive. Thus, the near-field probe structure 120 according to the first embodiment is manufactured.

  Next, a second embodiment will be described with reference to FIGS. 3A and 3B. FIG. 3A is a schematic diagram illustrating a configuration example of the near-field probe structure 120 of the AFM 10 according to the second embodiment (the near-field probe structure 120 according to the second embodiment), and FIG. It is the schematic which shows the example of a structure of the connection part of the near field probe structure 120 and the optical fiber 301 by 2 embodiment.

  Hereinafter, differences from the first embodiment will be mainly described. In order to avoid complication of description, members and structures corresponding to those of the first embodiment will be described using the same reference numerals as those of the first embodiment.

  The second embodiment is different from the first embodiment in the configuration of the near-field probe structure 120, and the other points are the same as the first embodiment. The overall configuration of the AFM 10 according to the second embodiment is similar to that of the first embodiment, and is shown in FIG.

  As the near-field probe structure 120 according to the second embodiment, a diamond rod 150 having a shape tapering toward the tip is used. The shape of the cross section (cross section) orthogonal to the length direction (extending direction) of the diamond rod 150 is not particularly limited, and is, for example, a circle or a polygon.

  Although the diamond rod 150 is configured as an integral (seamless) member in this example, as described below, from a functional point of view, the distal side portion 151 (130) and the root side portion 152 ( 140).

  The diameter of the tip side portion 151 of the diamond rod 150 is smaller than the wavelength of the excitation light 311 and is preferably 100 nm or less, more preferably 50 nm or less. Here, the “diameter of the diamond rod 150” is represented by the diameter of the smallest circle among the circles that can surround (can include) the cross section of the diamond rod 150.

  Distal portion 151 contains NV center 131, and preferably contains a single NV center 131.

  The root portion 152 of the diamond rod 150 disposed closer to the root than the distal portion 151 has a connection portion with the distal portion 151, that is, the diameter of the distal end is smaller than the wavelength of the excitation light 311. And preferably 100 nm or less, more preferably 50 nm or less. In addition, the diameter of the end on the root side is larger than the wavelength of the excitation light 311 and is, for example, about 5 μm.

  The root end of the root portion 152 is connected to the optical fiber 301. The optical fiber 301 may have various coating layers on the outer surface as needed.

  With such a configuration, the tip portion 151 of the diamond rod 150 functions as a diamond member containing the NV center 131, which is equivalent to the nanodiamond particles 130 in the first embodiment. In addition, the root side portion 152 of the diamond rod 150 functions as a light irradiation extraction member equivalent to the optical fiber probe 140 in the first embodiment.

  That is, the root-side portion (light-irradiation extraction member in the second embodiment) 152 (140) of the diamond rod 150 is the NV included in the tip-side portion (diamond member in the second embodiment) 151 (130) of the diamond rod 150. The center 131 is irradiated with the excitation light 311 under the near field, and the tip side portion 151 (130) of the diamond rod 150 is irradiated with the excitation light 311 so that the fluorescence 321 generated under the near field can be extracted from the NV center 131. It is configured as a member that is fixedly arranged (with a fixed positional relationship).

  As described above, in the near-field probe structure 120 according to the second embodiment, the tip-side portion 151 (130) as the diamond member containing the NV center 131 is different from the base-side portion 152 (140) as the light irradiation extraction member. A diamond rod 150, which is a structure disposed on the tip side, is used.

  In order to stabilize the behavior as a sensor, the NV center 131 is located within a range of 3 nm to 10 nm as a height (depth) from the tip on the tip side of the tip portion 151 (for example, about 5 nm). Is preferable.)

  Further, it is preferable that the spin direction of the NV center 131 is parallel to the direction of the static magnetic field 501 applied from the magnetic field application device 500, that is, for example, parallel to the Z direction.

  In order to make the spin of the NV center 131 parallel to the Z direction, it is preferable that the spin of the NV center 131 be parallel to the normal direction of the end face of the front end portion 151 on the front end side.

  FIG. 3B is a schematic view of a connection portion between the optical fiber 301 and the root-side portion 152 of the diamond rod 150 as viewed in a line parallel to the axial direction of the optical fiber 301. The root-side end surface of the root-side portion 152 preferably has a shape that matches the shape of the end surface of the core 302 of the optical fiber 301 or is included in the end surface of the core 302. This is for increasing the efficiency of the fluorescence 321 entering the optical fiber 301 from the diamond rod 150 to the core 302.

  It is preferable that a reflection film 160 is formed on the outer surface of the diamond rod 150 in order to reflect the excitation light 311 and the fluorescence 321 inward. The reflection film 160 is composed of, for example, a gold layer having a thickness of about 5 nm. Since the conductive film 160 is formed on the outer surface of the near-field probe structure 120, the near-field probe structure 120 can be used in a probe mechanism of a scanning tunneling microscope (STM).

  Note that an opening is formed in the reflection film 160 at the tip of the tip portion 151 of the diamond rod 150, that is, the tip portion 151 of the diamond rod 150 and the sample 20 can face each other without the reflection film 160 interposed therebetween. preferable. This is for suppressing the interaction between the reflection film 160 and the magnetic field of the sample 20 or the like.

  Next, an example of a method for manufacturing the near-field probe structure 120 according to the second embodiment will be described with reference to FIGS. 4A to 4D and FIGS. 5A to 5D. 4 (a) to 4 (d) and FIG. 5 (a) are schematic perspective views of a base material 170 forming the diamond rod 150, and FIGS. 5 (b) to 5 (d) show the diamond rod 150. It is the schematic sectional drawing seen from the side of 150.

  Referring to FIG. A base material 170 made of diamond is prepared. The surface (main surface) of base material 170 is preferably a (111) plane. The size of the base material 170 is, for example, 2 mm square and 100 μm in thickness.

  For example, nickel is vapor-deposited on each position of the surface of the base material 170 where the diamond rod is to be formed to form the mask 171. Each mask 171 has a diameter of, for example, 5 μm.

  Referring to FIG. For example, the base material 170 is anisotropically etched from the surface side by reactive ion etching (RIE) using a mixed plasma gas of oxygen and argon to form the diamond rod 150a below each mask 171. The height (length) of each diamond rod 150a is, for example, 100 μm.

  Referring to FIG. The mask 171 is removed from the base material 170.

FIG. 4D is referred to. Nitrogen ions (N ⁺ ) are implanted into the upper surface of each diamond rod 150a. The conditions for the ion implantation are, for example, an incident energy of 10 keV and a dose of 10 ¹² / cm ² . By adjusting the dose, about one NV center can be contained in one diamond rod 150a. Further, by adjusting the incident energy, the NV center can be located within a desired depth range from the end of the diamond rod 150a.

  Referring to FIG. The NV center 131a is formed on each diamond rod 150a by annealing the base material 170 at, for example, 850 ° C. for 2 hours.

  All the spins at the NV center 131a point in the <111> direction in the diamond. Since there are four equivalent directions as the <111> direction, by using the base material 170 whose surface is the (111) plane, the NV center 131a having a spin oriented in the normal direction of the surface of the base material 170 is obtained. It can be obtained with a probability of 1/4.

  In this way, a base material 170 on which a plurality of diamond rods 150a that are candidates for the diamond rod 150 used in the near-field probe structure 120 is prepared.

  For each diamond rod 150a of the base material 170, a fluorescence intensity spectrum was measured, observation was performed by a confocal microscope, and observation of an anti-bunching signal was performed by a photon correlation method. Is selected at a depth of 3 nm to 10 nm as described above, and the diamond rod 150 whose spin at the NV center 131 is parallel to the Z direction (parallel to the normal direction of the surface of the base material 170) is selected.

  Referring to FIG. FIG. 5B is a schematic diagram showing a cross-sectional shape of the diamond rod 150 as viewed from the side. The diamond rods shown in FIGS. 4B to 5A have a constant diameter for convenience of illustration, but in fact, the closer to the upper side of the base material (the side where etching is started), the more the diamond rod 150 The diameter is small.

  Referring to FIG. The upper portion of the selected diamond rod 150 is reduced in diameter and sharpened with a focused ion beam (FIB), thereby forming a tip-side portion 151 (130). After that, the diamond rod 150 is cut off from the base material 170.

  FIG. 5D is referred to. The diamond rod 150 is attached to the optical fiber 301 by, for example, an adhesive. Further, a gold layer is deposited on the outer surface of the diamond rod 150, and the gold layer is removed so that an opening is formed at the tip of the diamond rod 150, thereby forming the reflection film 160. It is preferable that the end face on the tip end side of the diamond rod 150 and the end face of the reflective film 160 have the same height (they are flush). The end face on the tip side of the diamond rod 150 is a (111) plane. Thus, the near-field probe structure 120 according to the second embodiment is manufactured.

  Next, effects obtained by the first and second embodiments will be exemplarily described. The first and second embodiments may be collectively referred to simply as an embodiment.

  The near-field probe structure 120 according to the embodiment includes a diamond member (the nanodiamond particles in the first embodiment, the tip side portion of the diamond rod 150 in the second embodiment) 130 containing the NV center 131, and a near-field near the NV center 131. A light irradiation / extraction member fixed to the diamond member 130 so as to irradiate the excitation light 311 below and extract the fluorescence 321 generated in the near field from the NV center 131 by the excitation light 311 ( An optical fiber probe according to the first embodiment, and a base portion 140 of the diamond rod 150 according to the second embodiment.

  With such a near-field probe structure 120, the AFM 10 according to the embodiment can be used for measuring a magnetic field, a temperature, an electric field, and the like using the NV center 131 as a sensor.

  Here, a conventionally used technique is to irradiate excitation light to the center of the NV through an objective lens, and collect and detect fluorescence from the center of the NV through the objective lens. The technology is a comparative form.

  In the comparative embodiment, since the light collection efficiency of the objective lens is low in the fluorescence detection (the upper limit of NA is about 1.45), only less than 1% of the total fluorescence can be detected.

  In the comparative embodiment, for example, when excitation light having a wavelength of 532 nm is used, the size of the light irradiation region cannot be made smaller than 300 nm due to a diffraction limit. For this reason, the excitation light is selectively irradiated to a limited area having a size sufficiently smaller than the wavelength of the excitation light (of visible light), for example, 100 nm or less (hereinafter, referred to as a limited area having a nanometer size). Can not do it.

  Further, in the comparative embodiment, since an optical system including an objective lens is required, it is difficult to reduce the size and the complexity of the apparatus.

  On the other hand, in the embodiment, as described above, by using the near-field probe structure 120, light irradiation detection under a near-field can be performed.

  That is, in the embodiment, the fluorescence 321 generated under the near field can be extracted from the NV center 131 by the light irradiation extraction member 140. This makes it possible to increase the fluorescence detection efficiency by several tens to several hundreds (to several tens of percent) as compared with the technology of collecting and detecting the fluorescence from the center of the NV with the objective lens as in the comparative embodiment. .

  Further, in the embodiment, the light irradiation / extraction member 140 can selectively irradiate the excitation light 311 to a limited area of a nanometer size. That is, it is possible to efficiently irradiate the excitation light 311 to the specific NV center 131 arranged in the limited area of the nanometer size.

  Further, in the embodiment, since the optical system including the objective lens is not required, the device can be easily reduced in size and combined. There is no need to position the objective lens. For this reason, for example, light irradiation and light detection in a place invisible from the outside, such as measurement in an extremely low temperature environment, are facilitated.

  In the second embodiment, by using the diamond rod 150 for the near-field probe structure 120, the diamond member (the tip side portion of the diamond rod 150) 130 and the light irradiation / extraction member (the root side portion of the diamond rod 150) 140 are formed. It is integrated. For this reason, there is no need to attach the diamond member (nano diamond particles) 130 and the light irradiation / extraction member (optical fiber probe) 140 as in the first embodiment.

  Further, since the mounting operation is not required, it is possible to avoid a positional shift between the diamond member 130 and the light irradiation / extraction member 140 due to the mounting operation. That is, in the second embodiment, the position of the NV center 131 in the near-field probe structure 120 is easier to control than in the first embodiment.

  In the first embodiment, the directions of the spins at the NV center of the plurality of nanodiamond particles that are candidates to be attached to the near-field probe structure 120 and dispersed on the support substrate are random. On the other hand, in the second embodiment, by using the base material 170 whose surface is the (111) plane, the spin directions of the NV centers of the plurality of diamond rods that are candidates for the near-field probe structure 120 are set to 1 It faces the normal direction of the base material surface with a probability of / 4. Therefore, in the second embodiment, it is easier to obtain the NV center 131 having a spin parallel to the Z direction, as compared with the first embodiment.

  As described above, the present invention has been described according to the embodiments, but the present invention is not limited to these. For example, it will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

  For example, in the above-described embodiment, as an example of the scanning probe microscope, the FM-AFM having the tuning-fork type quartz oscillator is illustrated, but another type of oscillator may be used. Further, an AFM of a type other than the FM-AFM may be used. Further, a scanning probe microscope of a type other than the AFM, for example, a scanning tunnel microscope (STM) may be used. Thus, the near-field probe structure according to the above-described embodiment can be used for the probe mechanism of various types of scanning probe microscopes.

  Hereinafter, preferred embodiments of the present invention will be additionally described.

(Appendix 1)
A diamond member containing a nitrogen-vacancy composite center;
The diamond member so that the center of the nitrogen-vacancy complex is irradiated with excitation light under a near field, and the excitation light can extract fluorescence generated under the near field from the center of the nitrogen-vacancy complex. A light irradiation extraction member fixedly arranged with respect to,
Near-field probe structure having:

(Appendix 2)
The near-field probe structure of claim 1, wherein the diamond member contains a single center of the nitrogen-vacancy complex.

(Appendix 3)
The light irradiation extraction member is an optical fiber probe,
3. The near-field probe structure according to claim 1, wherein the diamond member is a nanodiamond particle attached to a tip portion of the optical fiber probe.

(Appendix 4)
4. The near-field probe structure according to claim 3, wherein the center of the nitrogen-vacancy complex is located within a range of 3 nm to 10 nm in depth from a tip end of the nanodiamond particles.

(Appendix 5)
The near-field probe structure according to appendix 3 or 4, wherein a spin direction of the center of the nitrogen-vacancy complex is parallel to an extending direction of a tip portion of the optical fiber probe.

(Appendix 6)
The light irradiation take-out member is connected to an optical fiber and is a root side portion of a diamond rod having a shape that becomes thinner toward the tip,
The near-field probe structure according to appendix 1 or 2, wherein the diamond member is a tip-side portion disposed closer to a tip-side than the root-side portion of the diamond rod.

(Appendix 7)
7. The near-field probe structure according to appendix 6, wherein the center of the nitrogen-vacancy complex is located within a range of 3 nm to 10 nm in depth from a distal end of the distal portion.

(Appendix 8)
The near-field probe structure according to Supplementary Note 6 or 7, wherein an end face on the tip side of the tip side portion is a (111) plane.

(Appendix 9)
The near-field probe structure according to any one of appendices 6 to 8, wherein a spin direction of the center of the nitrogen-vacancy complex is parallel to a normal direction of an end face on a tip side of the tip portion.

(Appendix 10)
The near-field probe structure according to any one of supplementary notes 6 to 9, wherein a root-side end surface of the root-side portion has a shape that matches the shape of the end surface of the core of the optical fiber or is included in the end surface of the core. .

(Appendix 11)
The near-field probe structure according to any one of supplementary notes 6 to 10, wherein a reflection film that reflects light inward is formed on an outer surface of the diamond rod.

(Appendix 12)
The near-field probe structure according to appendix 11, wherein an opening is formed in the reflection film at a tip of the tip side portion.

(Appendix 13)
A probe mechanism used to observe the sample,
A scanning mechanism for controlling a relative position between the sample and the probe mechanism,
Has,
The probe mechanism,
A diamond member containing a nitrogen-vacancy composite center;
The diamond member so that the center of the nitrogen-vacancy complex is irradiated with excitation light under a near field, and the excitation light can extract fluorescence generated under the near field from the center of the nitrogen-vacancy complex. A light irradiation extraction member fixedly arranged with respect to,
A scanning probe microscope having a near-field probe structure having:

(Appendix 14)
The scanning probe microscope of claim 13, wherein the diamond member contains a single center of the nitrogen-vacancy complex.

(Appendix 15)
The light irradiation extraction member is an optical fiber probe,
15. The scanning probe microscope according to claim 13, wherein the diamond member is a nano diamond particle attached to a tip portion of the optical fiber probe.

(Appendix 16)
The light irradiation take-out member is connected to an optical fiber and is a root side portion of a diamond rod having a shape that becomes thinner toward the tip,
15. The scanning probe microscope according to claim 13 or 14, wherein the diamond member is a distal end portion disposed closer to a distal end side than the root side portion of the diamond rod.

(Appendix 17)
A light source for emitting the excitation light,
A detector for detecting the fluorescence,
The scanning probe microscope according to any one of supplementary notes 13 to 16, further comprising:

(Appendix 18)
The scanning probe microscope according to any one of supplementary notes 13 to 17, further comprising a microwave source for irradiating a microwave to the center of the nitrogen-hole complex.

(Appendix 19)
19. The scanning probe microscope according to any one of supplementary notes 13 to 18, further comprising a magnetic field application device that applies a magnetic field.

(Appendix 20)
20. The scanning probe microscope according to claim 19, wherein a spin direction of the center of the nitrogen-vacancy complex is parallel to a magnetic field applied by the magnetic field applying device.

(Appendix 21)
The scanning probe microscope according to any one of supplementary notes 13 to 20, wherein the scanning probe microscope is an atomic force microscope.

(Appendix 22)
The scanning probe microscope according to any one of supplementary notes 13 to 21, wherein the scanning probe microscope is a frequency modulation type atomic force microscope.

(Appendix 23)
On the outer surface of the near-field probe structure, a conductive film is formed,
21. The scanning probe microscope according to any one of supplementary notes 13 to 20, wherein the scanning probe microscope is a scanning tunnel microscope.

10 Atomic force microscope (scanning probe microscope)
Reference Signs List 20 Sample 100 Probe mechanism 110 Quartz crystal unit 120 Near-field probe structure 130 Diamond member, nanodiamond particles, tip part 131 of diamond rod NV center 140 Light irradiation extraction member, optical fiber probe, root part of diamond rod 150 Diamond rod 151 Diamond rod tip side portion 152 Diamond rod root side portion 200 Scanning mechanism 300 Light irradiation detection device 301 Optical fiber 311 Excitation light 321 Fluorescence 400 Microwave source 500 Magnetic field application device

Claims (8)

A diamond member containing a nitrogen-vacancy composite center;
The diamond member so that the center of the nitrogen-vacancy complex is irradiated with excitation light under a near field, and the excitation light can extract fluorescence generated under the near field from the center of the nitrogen-vacancy complex. A light irradiation extraction member fixedly arranged with respect to,
Has,
The light irradiation take-out member is connected to an optical fiber and is a root side portion of a diamond rod having a shape that becomes thinner toward the tip,
The diamond member is a tip side portion disposed closer to the tip side than the root side portion of the diamond rod, and contains a single nitrogen-vacancy complex center,
On the outer surface of the diamond rod, a reflection film that reflects light inward is formed,
A near-field probe structure, wherein an opening is formed in the reflective film at a tip of the tip side portion of the diamond rod. A probe mechanism used to observe the sample,
A scanning mechanism for controlling a relative position between the sample and the probe mechanism,
A light irradiation detection device,
Has,
The probe mechanism,
A diamond member containing a nitrogen-vacancy composite center;
The diamond member so that the center of the nitrogen-vacancy complex is irradiated with excitation light under a near field, and the excitation light can extract fluorescence generated under the near field from the center of the nitrogen-vacancy complex. A light irradiation extraction member fixedly arranged with respect to,
Having a near-field probe structure having
The light irradiation detection device,
A light source for emitting the excitation light,
A detector for detecting the fluorescence,
An optical fiber having one end connected to the light source and the detector, and the other end connected to the light irradiation extraction member;
Has,
The light irradiation take-out member is connected to the optical fiber and is a root side portion of a diamond rod having a shape that becomes thinner toward the tip,
The diamond member is a tip side portion disposed closer to the tip side than the root side portion of the diamond rod,
On the outer surface of the diamond rod, a reflection film that reflects light inward is formed,
A scanning probe microscope , wherein an opening is formed in the reflection film at a tip of the tip side portion of the diamond rod .   The scanning probe microscope according to claim 2, wherein the diamond member contains a single center of the nitrogen-vacancy complex. 4. The scanning probe microscope according to claim 2, wherein an end face on the tip side of the tip side portion is a (111) plane. The scanning probe microscope according to any one of claims 2 to 4 , further comprising a microwave source for irradiating the center of the nitrogen-vacancy complex with microwaves. The scanning probe microscope according to any one of claims 2 to 5 , further comprising a magnetic field application device that applies a magnetic field. The scanning probe microscope according to any one of claims 2 to 6 , wherein the scanning probe microscope is an atomic force microscope. The scanning probe microscope according to any one of claims 2 to 7 , wherein the scanning probe microscope is a frequency modulation type atomic force microscope.

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