Measurement methods for 3D active-site.

Flourescent X-rays Holography  (SPring-8 / KEK-PF)

Samples
Single Crystals and Doped in single crystals [1,2]
Epitaxial thin films and dopants in the films
mixed crystals, heterogeneous systems[3,4]
Typical Sample Size:     500μm or larger
Requirements:
Targets are limited to elements which generate flourescent X-rays
Minimum concentration of dopants:  0.05at%
Typical Duration:    3 days (9shifts in SPring-8)
Atomic Resolution:    ~0.5Å  (as width of atomic images)
Expected results :      
3D atomic arrangements around a target element (dopants) within 20Å
Local atomic distortion by doping
precursor phenomenon of atomic arrangements of phase transitions
Fluctuations of atomic positions


For more details, please contact a member of 05 Flouorensce X-rays Holography group

[1]Dopant:Extent and feature of lattice distortions around Ga impurity atoms in InSb single crystal, S. Hosokawa et al., Physical Review B 87, 094104 (2013).
[2] Phase Transition:Phase transition in Ti50Ni44Fe6 studied by x-ray fluorescence holography, W. Hu et al., Physical Review B, 80 (2009) 060202(R).
[3] Mixed Crystals:Reconciling the Pauling bond length picture and Vegard's law in a mixed crystal: An x-ray fluorescence holographic study, S.  Hosokawa, et al., Physical Review B 80, (2009) 134123.
[4] Acute and obtuse rhombohedrons in the local structures of relaxor ferroelectric Pb(Mg1/3Nb2/3)O3, Wen Hu, et al, Physical Review B 89, 140103(R) (2014).


Photoelectron Holography (SPring-8)

Samples
Single Crystals and Doped in single crystals [1,2]
Epitaxial thin films and dopants in the films
Adsorbates on surface of crystals
Typical Sample Size:          200μm or larger
Requirements:
Materials which have electric conduction, even with high resistivity
It can be treated in vacuum
Clean surface
Minimum concentration of dopants:  0.5at%
Typical Duration:                2〜3days (6-9 shifts in SPring-8)
Atomic Resolution:             ~0.5Å (as width of atomic images)
Expected results
Area with 10Å thickness from the surface can be observed.
3D atomic images in an area with a radius of 10
Å around a target (impurity, adsorbates, Interface atoms)
Simultaneous measurements of XAFS and 3D atomic images of target elements

For more details, please contuct a member of 06 Photoelectron Holography   

CTR Scattering method (SPring-8/KEK-PF)

Samples
Not limited to Si, Au, and other simple materials.
Ultrathin films of perovskites oxides[1],
Topological insulator[2],
Organic semiconductors[3], etc. are measured.
Typical Sample Size:  2*2mm2 or larger
Requirements
Single crystals whose surface is as flat as step & terrace structure.
Typical Duration
2-3days (SPring-8 BL13XU is recommended(6-9 shifts))
3-4days(KEK-PF BL-3A, 4C are recommended)
Atomic Resolution:  0.1Å or better
Expected results
Depth profile of the electron-density is observed. Depth dependent structure anlysis can be performed. ~4nm depth (10 unit cell depth for perovskite) is the typical maximum range of the analysis. Interfaces of solid-liquid phases can be observed. This method observes averaged structures of in-plane direction, which makes it possible to clarify the overall structure. In turn, it is insensitive to small amount of absobates. This method is non-destructive method, which is very different from the cross-sectional TEM.


For more details, please contuct a member of 07 Surface/interface holography   

[1] R.Yamamoto,Y.Wakabayashi et al. Phys. Rev. Lett. 107 036104 (2011).
[2] T. Shirasawa, T. Takahashi, et al. Phys. Rev. B 87 075449 (2013).
[3] Y.Wakabayashi et al., Phys. Rev. Lett. 104, 066103 (2010).


Diffractive Imaging (electron microscope)

Samples

Crystalline and non-crystalline nano-materials which have electron transparency.

Carbon materials such as graphene, nanotube, and so on.

Atoms, moleculars, polymers on Graphene

Dopants in semiconductor,
Electromagnetic field

Typical Sample Size:10~100 nm or smaller (on 3mm grids)
Requirements
Basically same as requiments for transmission electron microscopes
Typical Duration:  1~2 min. (+ 1day for sample preparation)     
Atomic Resolution: ~1Å
Expected results
Atomic Arrangements, Identification of atoms, Distribution of electromagnetic field

For more details, please contuct a member of 08 Nano-structure Imaging.

[1]S. Hattanda, H. Shioya, Y. Maehara, and K. Gohara: K-means clustering for support construction in diffractive imaging, J. Opt. Soc. Am. A, 31(3), 470, 2014.
[2]O. Kamimura, Y. Maehara, T. Dobashi, K. Kobayashi, R. Kitaura, H. Shinohara, H. Shioya, and K. Gohara: Low-voltage electron diffractive imaging of atomic structure in single-wall carbon nanotubes , Appl. Phys. Lett., 98(17), 174103, 2011.
[3]K. Kawahara, K. Gohara, Y. Maehara, T. Dobashi, and O. Kamimura: Beam-divergence deconvolution for diffractive imaging, Phys. Rev. B, 81(8),081404(R), 2010.