Morishita Shigeyuki, Mukai Masaki, Suenaga Kazu, Sawada Hidetaka
JEOL Limited, 3-1-2 Musashino, Akishima, Tokyo 196-8558, Japan.
National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan.
Phys Rev Lett. 2016 Oct 7;117(15):153004. doi: 10.1103/PhysRevLett.117.153004. Epub 2016 Oct 6.
Transmission electron microscopy using low-energy electrons would be very useful for atomic resolution imaging of specimens that would be damaged at higher energies. However, the resolution at low voltages is degraded because of geometrical and chromatic aberrations. In the present study, we diminish the effect of these aberrations by using a delta-type corrector and a monochromator. The dominant residual aberration in a delta-type corrector, which is the sixth-order three-lobe aberration, is counterbalanced by other threefold aberrations. Defocus spread caused by chromatic aberration is reduced by using a monochromated beam with an energy spread of 0.05 eV. We obtain images of graphene and demonstrate atomic resolution at an ultralow accelerating voltage of 15 kV.
使用低能电子的透射电子显微镜对于那些在较高能量下会受损的标本进行原子分辨率成像非常有用。然而，由于几何像差和色差，低电压下的分辨率会降低。在本研究中，我们通过使用δ型校正器和单色仪来减小这些像差的影响。δ型校正器中的主要残余像差，即六阶三瓣像差，被其他三重像差所抵消。通过使用能量分散为0.05 eV的单色光束，可减少色差引起的散焦扩展。我们获得了石墨烯的图像，并在15 kV的超低加速电压下展示了原子分辨率。
