Determination of molecular ordering at a buried interface and the effect of interfacial ordering on thin film...

It is demonstrated that by using optical second harmonic generation the orientation and alignment of molecules in the interfacial layer between two solids, a thin solid molecular film and a metal substrate, can be determined. The pyridine molecules in the interfacial layer underneath the film are found to align along the [110] direction of the Ag(110) surface with a small tilt angle (approximately 11 degrees) from the surface normal. This interfacial ordering is found to have a notable effect in inducing crystallization at the heterogeneous boundary of the amorphous molecular film.