Variable period X-ray standing wave (XSW) measurements have been used previously to monitor and to interpret structure rearrangements undergone during a phase transition in a model membrance with angstrom resolution. In the present study,an extended length scale ranging from 40 up to ca. 1000 A has been used without sacrificing resolution to address the question of whether the phase transition characteristics of a lipid multilayer are sensitive to the number and identity of the lamellae in the membrane stack. The system chosen for examination consisted of an octadecanethiol (ODT) coated gold mirror on top of which a variable number (0,2,8, and 16) of ω-tricosenoic acid (C23, ωTA) bilayers followed by a single upper inverted bilayer of zinc arachidate (C20, ZnA) was deposited by the Langmuir-Blodgett (LB) technique. Variable period XSW measurements provided precise information on the zinc layer mean position and width and were used to track the collapse of the heavy atom layer during the thermotropic phase transition.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry