Adsorption behavior of counterions under a Langmuir monolayer was investigated by sum-frequency generation (SFG) spectroscopy. By comparing SFG spectra of arachidic acid (AA) Langmuir monolayer/water interface with and without added salt, it was found that the simple trivalent cation La3+ adsorbed on AA monolayer only when the carboxylic headgroups are charged (deprotonated), implying that counterion adsorption is induced by Coulomb interaction. On the other hand, metal hydroxide complex Fe(OH)3 adsorbed even on a charge-neutral AA monolayer, indicating that the adsorption of iron hydroxide is due to chemical interaction such as covalent or hydrogen bonding to the headgroup of the molecules at the monolayer.
© 2013 Optical Society of Korea
Original Manuscript: October 30, 2012
Revised Manuscript: January 14, 2013
Manuscript Accepted: January 16, 2013
Published: February 25, 2013
Woongmo Sung, David Vaknin, and Doseok Kim, "Different Adsorption Behavior of Rare Earth and Metallic Ion Complexes on Langmuir Monolayers Probed by Sum-Frequency Generation Spectroscopy," J. Opt. Soc. Korea 17, 10-15 (2013)
References are not available for this paper.