February 7, 2012
From left: Assoc. Prof. Kurata,
Dr. M. Haruta
Dr. Mitsutaka Haruta (presently, in NIMS) and Assoc. Prof. Horoki Kurata (Institute for Chemical Research) demonstrated the direct observation of molecular column in organic crystals using a scanning transmission electron microscope. They found a new type of crystal defect in the grain boundaries. This work has been published in Scientific Reports on February 7, 2012.
Atomic resolution images of copper hexachlorophthalocyanine (C16CuPc) thin films have been observed by the annular bright field (ABF) and annular dark field (ADF) imaging using an aberration-corrected scanning transmission electron microscope equipped with a nano-tip field emission gun. By using the low-dose technique and an optimized detection angle, we were able to visualize the contrast of light element (C and N) together with the heavier elements (Cl and Cu) within the molecular column. We were also able to identify unexpected molecular orientation in the grain boundaries along the {110} crystallographic planes giving rise to stacking faults.
- Figure 1: (a) Annular bright field image of C16CuPc crystal. (b) Annular dark field image of C16CuPc crystal. (c) Annular dark field image of complex defect region. The stacking fault was observed along the (110) plane and C16CuPc molecules with irregular orientation were identified in the grain boundary (GB) as a line contrast.
Link to the journal paper:
http://dx.doi.org/10.1038/srep00252
http://hdl.handle.net/2433/152829 (Research Information Repository KURENAI)
"Direct observation of crystal defects in an organic molecular crystals of copper hexachlorophthalocyanine by STEM-EELS"
Mitsutaka Haruta, Hiroki Kurata
Scientific Reports, 2, 252; DOI:10.1038/srep00252 (2012).