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  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 .
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 JSPS KAKENHI is acknowledged for financial support.