Macroscopic and microscopic surface characterization of a vitamin K 1 monolayer on water

Abstract

Film pressure and surface potential measurements are used to elucidate chain orientational changes in vitamin K 1 and phytol monolayers during compression and expansion cycles. Second harmonic generation studies on vitamin K 1 show a major reorientation in the quinone head group during compression. In the expanded film, phytol chains are freely rotating and head groups are randomly oriented. Upon compression, the short axis of the quinone head groups orients with a tilt angle of 24° to the surface normal. Molecular interactions may cause the surface potential to change as chains become more nearly vertically oriented.