“…First, the linear sloping plateau at A < A 0 resembles that observed at the same A-range for a mercury-supported stearic acid LF [15], which was shown to correspond to a continuous conversion with decreasing A of a monolayer to a bilayer of surface-parallel molecules. Second, no sharp rise, the sign of a transition from lying-down to standing-up molecules, is observed near film collapse at A ≤ 50Å 2 /molecule, in contrast with mercury-supported LFs of fatty acids, thiols, and alcohols [15,16], which show such transitions. These isotherm-derived inferences are confirmed by our x-ray measurements, discussed next.…”