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Name (Title):
Masato Nakaya (NIMS researcher)
Affiliation:
International Center for Materials Nanoarchitectonics
(MANA), NIMS
Address:
1-1 Namiki, Tsukuba. Ibaraki 305-0044, Japan
Email: NAKAYA.Masato@nims.go.jp
Home Page:
Presentation Title:
Reversibility–controlled chemical reaction between fullerene molecules
and its application for information storage devices
Abstract:
[Masato Nakaya, Masakazu Aono and Tomonobu Nakayama]
One of the attractive features of fullerene C60 molecules is that their functionality changes
depending on intermolecular chemical bonds. Thus, controlling chemical bonds formation
(polymerization) and annihilation (depolymerization) between C60 molecules at single molecule
level is of great interest for realizing nanoscale devices such as a stable switch and nonvolatile
memory cells. Here, we present methodology and application of the control of local
intermolecular reaction between C60 molecules using a tip of scanning tunneling microscope
(STM).
For experiments, we prepared C60 films formed on the highly oriented pyrolitic graphite
(HOPG) and on the Si(111)√3×√3R30˚−Ag surfaces. We can control polymerization and
depolymerization at room temperature only by selecting an appropriate bias voltage (Vs) applied
to the C60 film. At negative Vs, C60 molecules are efficiently reacted with each other via [2+2]
cycloaddition reaction beneath the tip (Fig. a−b). In contrast, the created [2+2] cycloadduct tends
to dissociate into monomers by applying positive Vs (Fig. b−c). Magnitude of Vs is also important
for controlling the spatial precision and the area of the STM–induced chemical reactions. By
setting the appropriate polarity and magnitude of the bias voltage, we can induce the
polymerization and depolymerization at designated single molecule beneath the tip. We also
demonstrate ultradense rewritable data storage into C60 films. Writing and erasing of digital data
were carried out by inducing polymerization and depolymerization in interlayer of C60 multilayer
film, respectively, realizing a bit density of 190 Tbits/inch 2 .
a b c
Figure. STM image of C60 film a before polymerization, b after polymerization
and c after depolymerization
Poster Session PS-7
77