pH-dependent kinetics of MgCl2 adsorption under a fatty-acid Langmuir film.
The effect of subphase pH (5.5 and 10.5) on the structure of behenic-acid monolayers was investigated during Mg(2+) adsorption by means of Grazing Incidence X-ray Diffraction (GIXD) and Brewster Angle Microscopy (BAM). The final phase corresponding to an ion superlattice commensurate to the behenic-acid cell is pH-independent. In contrast, the sequence of phases evidenced from the initial L(2)-phase to this final state presents at pH 10.5 an additional stage associated to a film condensation toward the L' (2)-phase. The structures of the intermediate states preceding the superstructure nucleation are slightly different, both with a short-range fatty-acid order. Finally, a laser light effect that could result from visible light absorption by the inorganic complexes is evidenced in the final state as well as in the intermediate phases.
Pignat
J
J
LPPI, Université de Cergy-Pontoise, 5 mail Gay-Lussac Neuville/Oise, 95031, Cergy-Pontoise Cedex, France.
Cantin
S
S
Liu
R C W
RC
Goldmann
M
M
Fontaine
P
P
Daillant
J
J
Perrot
F
F
D000327:Adsorption; D003198:Computer Simulation; D005227:Fatty Acids / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008051:Lipid Bilayers / Q000737:chemistry*; D015636:Magnesium Chloride / Q000737:chemistry*; D008567:Membranes, Artificial; D008956:Models, Chemical; D044367:Phase Transition
D005227:Fatty Acids; D008051:Lipid Bilayers; D008567:Membranes, Artificial; D015636:Magnesium Chloride