Single-Molecule Chemistry

Single molecules are the smallest building blocks of matter with chemical properties. The intrinsic properties of individual molecules cannot be understood in an ensemble of molecules where many properties are averaged and affected by local environment. We have investigated the nature of interaction between single molecules and surfaces from the chemistry point of view. The scanning tunneling microscope (STM) is a versatile and powerful tool for realizing the purpose of our study, not only because it can reveal images of individual molecules, but because it is now applicable to manipulation, chemical reaction, and probing quantum states of single molecules. Electronic, vibrational, or spin states are selectively excited with spectroscopy and sub-nanometer spatial resolution is realized.