X-RAY REFLECTION STUDY OF ADSORPTION OF A FLUOROSURFACTANT FROM AN ORGANIC SOLUTION

Using X-ray reflectivity, we studied the packing and coverage of a flu orosurfactant, F3C(CF2)(7)SO2N(C2H5)(CH2CH2O)((7.4))CH3, at the liquid /vapor interface of a saturated solution in decane at 20 degrees C. We found the coverage to be 34 Angstrom(2)/molecule, with the fluorocarb on segments in contact with the vapor phase, oriented along the surfac e normal and the ethylene oxide segments close-packed underneath. The orientation of the ethylene oxide segments must either be tilted at an angle of 36 degrees with respect to the surface normal or contain dec ane to ''expand'' the ethylene oxide layer.