Domain structure of 17,19-hexatriacontadiyne monolayers formed on graphite (0 0 0 1) surfaces studied by UHV-STM

Monolayers of 17,19-hexatriacontadiyne (HTDY) formed by vapor deposition onto graphite (0 0 0 1) surfaces were studied by scanning tunneling microscopy under ultrahigh vacuum. It has been found in a monolayer that HTDY molecules form lamella structures in which the alkyl chains are laid flat and arranged parallel to the graphite ag axis. From the six-fold symmetry of the graphite (0 0 0 1) surface and the C2h symmetry of the molecule, six directions of lamellae are possible. HTDY molecules have high mobility at room temperature and form large domains. The mobility of the molecules is relatively low under 200 K, resulting in small domains. With these observations, we can explain the temperature dependence of polymerization reactions taking place in an HTDY monolayer to form sashlike macromolecules.