AVS 46th International Symposium
    Surface Science Division Wednesday Sessions
       Session SS-WeP

Paper SS-WeP33
Composition and Orientation at the Surface of a Room-Temperature Ionic Liquid Observed by Direct Recoiling Spectrometry

Wednesday, October 27, 1999, 5:30 pm, Room 4C

Session: Poster Session
Presenter: P.R. Watson, Oregon State University
Authors: P.R. Watson, Oregon State University
T.J. Gannon, Oregon State University
G. Law, Oregon State University
A.J. Carmichael, Queen's University, Ireland
K.R. Seddon, Queen's University, Ireland
Correspondent: Click to Email
Direct recoil spectrometry (DRS) has recently been applied to investigate the structure and orientation at the surface of low vapor-pressure liquids. Room temperature ionic liquids are generating considerable interest as low vapor-pressure clean technology solvents. We report the first measurements of the composition and molecular orientation at the surface of the room temperature ionic liquid - 1-butyl-3-methylimidazolium hexafluorophosphate, [bmim][PF@sub6@]. Recoil spectrometry using rare gas ions on continuously refreshed liquid surfaces in vacuo shows that neither ion is significantly enriched in the surface. The average orientation of the cation is with the plane of the ring vertical. The cation ring is rotated about an axis through its center such that the nitrogen atoms and side chains are deeper in the surface with the surface normal passing between the two nitrogen atoms (with an estimated error of ±30°).