title: SERS Titration of 4-Mercaptopyridine Self-Assembled Monolayers at Aqueous Buffer/Gold Interfaces.
abstract: Determination of the surface pK(a) of self-assembled monolayers (SAMs) at aqueous buffer/gold interfaces using surface-enhanced Raman scattering (SERS) measurements, namely, SERS titration, is reported for the first time. From the analysis of pH-dependent SERS spectra of 4-mercaptopyridine monolayers on gold, the pK(1/2) (3.9 ± 0.2) was determined. By further correlating the surface pH value with the bulk pH value in terms of the Gouy-Chapmann model, the surface pK(a) (5.3 ± 0.3) was evaluated accordingly. Compared to the conventional contact angle titration, SERS titration has the advantage of giving further insight into the microscopic and dynamic information of the surface-confined functional groups. In addition, such a technique has high sensitivity, micrometer spatial resolution, and chemical selectivity.
authors.affiliation: Center for Intelligent Materials Research (CIMR), College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.
authors.forename: H Z
authors.initials: HZ
authors.lastname: Yu
authors.forename: N
authors.initials: N
authors.lastname: Xia
authors.forename: Z F
authors.initials: ZF
authors.lastname: Liu