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In-line three-dimensional holography of nanocrystalline objects at atomic resolution.

Chen FR, Van Dyck D, Kisielowski C - Nat Commun (2016)

Bottom Line: Resolution and sensitivity of the latest generation aberration-corrected transmission electron microscopes allow the vast majority of single atoms to be imaged with sub-Ångstrom resolution and their locations determined in an image plane with a precision that exceeds the 1.9-pm wavelength of 300 kV electrons.The method is compatible with low dose rate electron microscopy, which improves on signal quality, while minimizing electron beam-induced structure modifications even for small particles or surfaces.We apply it to germanium, gold and magnesium oxide particles, and achieve a depth resolution of 1-2 Å, which is smaller than inter-atomic distances.

View Article: PubMed Central - PubMed

Affiliation: Department of Engineering and System Science, National Tsing-Hua University, 101 Kuang-Fu Road, Hsin Chu 300, Taiwan.

ABSTRACT
Resolution and sensitivity of the latest generation aberration-corrected transmission electron microscopes allow the vast majority of single atoms to be imaged with sub-Ångstrom resolution and their locations determined in an image plane with a precision that exceeds the 1.9-pm wavelength of 300 kV electrons. Such unprecedented performance allows expansion of electron microscopic investigations with atomic resolution into the third dimension. Here we report a general tomographic method to recover the three-dimensional shape of a crystalline particle from high-resolution images of a single projection without the need for sample rotation. The method is compatible with low dose rate electron microscopy, which improves on signal quality, while minimizing electron beam-induced structure modifications even for small particles or surfaces. We apply it to germanium, gold and magnesium oxide particles, and achieve a depth resolution of 1-2 Å, which is smaller than inter-atomic distances.

No MeSH data available.


Related in: MedlinePlus

Effects of mechanical damping and potential softening to Argand plots.(a) Red Argand plot shows exit waves reconstructed from simulated images of Au [001] crystal with Debye–Waller (DW) factor of 0.5 Å2 with no mechanical damping (DM), whereas the green Argand plot is obtained from the same crystal but with mechanical damping (DM=50 pm) of the contrast transfer function. The numbers in the plot correspond to number of atom. (b) In our case, phases are reduced due to reversible electron beam-induced object excitations in the image formation process. This electron beam stimulation effect is modelled as a higher Debye–Waller factor of 16 Å2 with DM=0 pm.
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f5: Effects of mechanical damping and potential softening to Argand plots.(a) Red Argand plot shows exit waves reconstructed from simulated images of Au [001] crystal with Debye–Waller (DW) factor of 0.5 Å2 with no mechanical damping (DM), whereas the green Argand plot is obtained from the same crystal but with mechanical damping (DM=50 pm) of the contrast transfer function. The numbers in the plot correspond to number of atom. (b) In our case, phases are reduced due to reversible electron beam-induced object excitations in the image formation process. This electron beam stimulation effect is modelled as a higher Debye–Waller factor of 16 Å2 with DM=0 pm.

Mentions: It is instructive to investigate the impact of different damping functions on the signal strength using an Argand plot. Contribution from damping functions such as a poor modulation transfer function of a camera or mechanical vibrations, for example, simply reduce the diameter of the Argand circle but do not affect the phase change per atom as long as phase changes are measured from the centre of an Argand circle (Fig. 5a). The exit wave for the red Argand plot (Fig. 5a) is reconstructed from simulated images of a Au [001] crystal with a Debye–Waller factor of 0.5 Å2, whereas the green Argand plot is obtained with the same parameter set, except for an additional mechanical damping of the contrast transfer function by 50 pm, which coincides with the information limit resolution of TEAM 0.5. It is seen that the phase change per atom is maintained if measured from the origin of the Argand circle even though its diameter is largely reduced. Consequently, we do not correct for a poor camera performance or mechanical vibrations, because such corrections only boost high-frequency noise but leave phases unaffected if described in an Argand plot. Instead, we fit Argand circles to the data points and translate the origin of the circle to (0,0). On the other hand, damping processes such as electron beam-induced atom vibrations can soften the scattering potential and reduce the phase values for scattering at single atoms. If we model electron beam-induced object excitations of 45 pm by using a larger Debye–Waller factor of 16 Å2=8π2(45)  pm2 (ref. 41), the phases are greatly reduced, which leads to the blue circle in Fig. 5b. This description is consistent with the view that reversible electron beam-induced object excitations contribute to the image formation process. As such excitations can cause large displacements and decrease logarithmically with decreasing dose rates26, low dose rate electron microscope becomes advantageous or even mandatory if it is needed to maintain the pristine structure of small particles42, surfaces or even molecules43.


In-line three-dimensional holography of nanocrystalline objects at atomic resolution.

Chen FR, Van Dyck D, Kisielowski C - Nat Commun (2016)

Effects of mechanical damping and potential softening to Argand plots.(a) Red Argand plot shows exit waves reconstructed from simulated images of Au [001] crystal with Debye–Waller (DW) factor of 0.5 Å2 with no mechanical damping (DM), whereas the green Argand plot is obtained from the same crystal but with mechanical damping (DM=50 pm) of the contrast transfer function. The numbers in the plot correspond to number of atom. (b) In our case, phases are reduced due to reversible electron beam-induced object excitations in the image formation process. This electron beam stimulation effect is modelled as a higher Debye–Waller factor of 16 Å2 with DM=0 pm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4759637&req=5

f5: Effects of mechanical damping and potential softening to Argand plots.(a) Red Argand plot shows exit waves reconstructed from simulated images of Au [001] crystal with Debye–Waller (DW) factor of 0.5 Å2 with no mechanical damping (DM), whereas the green Argand plot is obtained from the same crystal but with mechanical damping (DM=50 pm) of the contrast transfer function. The numbers in the plot correspond to number of atom. (b) In our case, phases are reduced due to reversible electron beam-induced object excitations in the image formation process. This electron beam stimulation effect is modelled as a higher Debye–Waller factor of 16 Å2 with DM=0 pm.
Mentions: It is instructive to investigate the impact of different damping functions on the signal strength using an Argand plot. Contribution from damping functions such as a poor modulation transfer function of a camera or mechanical vibrations, for example, simply reduce the diameter of the Argand circle but do not affect the phase change per atom as long as phase changes are measured from the centre of an Argand circle (Fig. 5a). The exit wave for the red Argand plot (Fig. 5a) is reconstructed from simulated images of a Au [001] crystal with a Debye–Waller factor of 0.5 Å2, whereas the green Argand plot is obtained with the same parameter set, except for an additional mechanical damping of the contrast transfer function by 50 pm, which coincides with the information limit resolution of TEAM 0.5. It is seen that the phase change per atom is maintained if measured from the origin of the Argand circle even though its diameter is largely reduced. Consequently, we do not correct for a poor camera performance or mechanical vibrations, because such corrections only boost high-frequency noise but leave phases unaffected if described in an Argand plot. Instead, we fit Argand circles to the data points and translate the origin of the circle to (0,0). On the other hand, damping processes such as electron beam-induced atom vibrations can soften the scattering potential and reduce the phase values for scattering at single atoms. If we model electron beam-induced object excitations of 45 pm by using a larger Debye–Waller factor of 16 Å2=8π2(45)  pm2 (ref. 41), the phases are greatly reduced, which leads to the blue circle in Fig. 5b. This description is consistent with the view that reversible electron beam-induced object excitations contribute to the image formation process. As such excitations can cause large displacements and decrease logarithmically with decreasing dose rates26, low dose rate electron microscope becomes advantageous or even mandatory if it is needed to maintain the pristine structure of small particles42, surfaces or even molecules43.

Bottom Line: Resolution and sensitivity of the latest generation aberration-corrected transmission electron microscopes allow the vast majority of single atoms to be imaged with sub-Ångstrom resolution and their locations determined in an image plane with a precision that exceeds the 1.9-pm wavelength of 300 kV electrons.The method is compatible with low dose rate electron microscopy, which improves on signal quality, while minimizing electron beam-induced structure modifications even for small particles or surfaces.We apply it to germanium, gold and magnesium oxide particles, and achieve a depth resolution of 1-2 Å, which is smaller than inter-atomic distances.

View Article: PubMed Central - PubMed

Affiliation: Department of Engineering and System Science, National Tsing-Hua University, 101 Kuang-Fu Road, Hsin Chu 300, Taiwan.

ABSTRACT
Resolution and sensitivity of the latest generation aberration-corrected transmission electron microscopes allow the vast majority of single atoms to be imaged with sub-Ångstrom resolution and their locations determined in an image plane with a precision that exceeds the 1.9-pm wavelength of 300 kV electrons. Such unprecedented performance allows expansion of electron microscopic investigations with atomic resolution into the third dimension. Here we report a general tomographic method to recover the three-dimensional shape of a crystalline particle from high-resolution images of a single projection without the need for sample rotation. The method is compatible with low dose rate electron microscopy, which improves on signal quality, while minimizing electron beam-induced structure modifications even for small particles or surfaces. We apply it to germanium, gold and magnesium oxide particles, and achieve a depth resolution of 1-2 Å, which is smaller than inter-atomic distances.

No MeSH data available.


Related in: MedlinePlus