In order to model biological membranes, DPPE 2-dihexadecanoyl-sn-glyce
ro-3-phosphoethanolamine) and DPPC (1,2-dihexadecanoyl-sn-glycero-3-ph
osphocholine) Langmuir-Blodgett (LB) films were deposited on hydrophil
ic mica and hydrophobic highly ordered pyrolitic graphite (HOPG), and
subsequently characterized by atomic force microscopy (AFM) and X-ray
photoelectron spectroscopy(XPS). AFM was used to determine the topogra
phy and to monitor the stability of the deposited films in air and und
er water at varying experimental parameters. Angle-resolved XPS was us
ed to measure the mean thickness and the orientation of the deposit. M
onolayer transfer pressure was determined at 40 mN/m with molecular ar
ea at 0.42 +/- 0.02 nm(2) for DPPE and 0.55 +/- 0.02 nm(2) for DPPC. N
anometric resolution was achieved on DPPE crystal and LB films and all
owed the determination of the corresponding lattice constants a = 0.64
+/- 0.03 nm, b = 0.91 +/- 0.07 nm, and c = 5.6 +/- 0.2 nm and a = 0.6
8 +/- 0.02 nm, b = 0.93 +/- 0.05 nm, and c = 5.6 +/- 0.2 nm, respectiv
ely. The DPPE monolayer on mica was measured to be 2.7 +/- 0.2 nm thic
k and the surface was hydrophobic. The reorganization of DPPE bilayer
when going from the water to the air was directly observed to form mon
olayer and trilayer domains. On HOPG, the outermost layer of DPPE was
partly hydrophilic and partly hydrophobic. Under the same conditions o
f deposition, DPPC formed a mixed structure of flat domains and vesicl
es. In water, monolayer aliphatic tail ending is less compact and pres
ents a higher friction coefficient than polar heads as measured by lat
eral force AFM.