Abstract
Homo- and heterochiral Langmuir films of a chiral derivative of stearic acid are studied in situ on the surface of liquid mercury as a function of surface coverage by surface tensiometry and surface-specific synchrotron X-ray diffraction and reflectivity. A transition from a phase of surface-parallel molecules to a phase of standing-up molecules is found. The former shows no surface-parallel long-range order. The standing-up phase of both homochiral and heterochiral compositions exhibit long-range order. However, the former has an oblique unit cell with parallel molecular planes, and the later has a centered rectangular unit cell with a herringbone molecular packing. For both cases, the standing-up molecules are tilted by 44° from the surface normal and pack at a density of 19.5 Å 2/molecule in the plane normal to the molecular long axis. Important differences are found, and discussed, between this behavior and that of a Langmuir film of the nonchiral stearic acid on mercury.
Original language | English |
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Pages (from-to) | 5111-5119 |
Number of pages | 9 |
Journal | Langmuir |
Volume | 25 |
Issue number | 9 |
DOIs | |
State | Published - 5 May 2009 |