State-selective dissociation of a single water molecule on an ultrathin MgO film

• Published in: Nature materials Vol. 9; no. 5; pp. 442 - 447
• Main Authors: Kim, Yousoo, Kawai, Maki, Shin, Hyung-Joon, Jung, Jaehoon, Motobayashi, Kenta, Yanagisawa, Susumu, Morikawa, Yoshitada
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.05.2010; Nature Publishing Group
• Subjects: 639/301/119/544; 639/301/299; Biomaterials; Chemical reactions; Chemistry and Materials Science; Condensed Matter Physics; Electronics; Excitation; Low temperature; Magnesium oxide; Materials Science; Microscopy; Molecules; Nanotechnology; Optical and Electronic Materials; Oxides; Pathways; Scanning tunneling microscopy; Substrates; Thin films; Tunnelling
• DOI: 10.1038/nmat2740
• ISSN: 1476-1122

The interaction of water with oxide surfaces has drawn considerable interest, owing to its application to problems in diverse scientific fields. Atomic-scale insights into water molecules on the oxide surface have long been recognized as essential for a fundamental understanding of the molecular processes occurring there. Here, we report the dissociation of a single water molecule on an ultrathin MgO film using low-temperature scanning tunnelling microscopy. Two types of dissociation pathway—vibrational excitation and electronic excitation—are selectively achieved by means of injecting tunnelling electrons at the single-molecule level, resulting in different dissociated products according to the reaction paths. Our results reveal the advantage of using a MgO film, rather than bulk MgO, as a substrate in chemical reactions. Understanding the interaction of water with oxide surfaces at the molecular level could prove to be significant for controlling the catalytic activity of complex nanoparticles on insulating films. Two types of selective dissociation pathway involving electronic and vibrational excitation are now observed for a single water molecule on MgO thin films.