Kazutomo Suenaga1

1, AIST, Tsukuba, Ibaraki, Japan

Properties of low-dimensional materials are largely influenced by its structural imperfections, such as defects, impurities, edges or boundaries. Hence, analytical technique at the single-atom level is becoming crucial to fully understand their physical/chemical performance. In my presentation, single atom spectroscopy by means of electron energy-loss spectroscopy (EELS) will be shown to discriminate individual atoms in low-dimensional materials at their interrupted periodicities. It is emphasized here that information of the bonding/electronic states has become accessible for single atoms through the EELS fine-structure analysis [1] as well as the spin state [2, 3]. Large variations of local electronic properties of 1D and 2D materials with different atomic coordinates will be investigated [4, 5].
I will also show some examples for the optical-range electron-spectroscopy of low-dimensional materials [6, 7, 8]. Differences between EELS and optical absorption will be discussed for surface materials in diluted systems [9].

[1] YC. Lin et al., Nano Lett., 15 7408-7413 (2015).
[2] YC. Lin et al., Phys. Rev. Lett., 115 206803 (2015).
[3] G. Liu et al., Nature Chem. 9 810-816 (2017).
[4] YC. Lin et al., Nano Lett., 17 494-500 (2017).
[5] HP. Komsa et al., Nano Lett., 17 3694-3700 (2017).
[6] R. Senga et al., Nano Lett., 16 3661-3667 (2016).
[7] J. Lin et al., Nano Lett., 16 7198-7202 (2016).
[8] L. Tizei et al., Phys. Rev. Lett., 114 107601 (2015).
[9] R. Senga et al., (unpublished)
[9] JSPS KAKENHI is acknowledged for financial support.