In situ monitoring of the change in extinction of stabilized nanoscopic cold particles in contact with aqueous phenol solutions

Changes to the surface plasmon resonance band of stable nanoscopic gold par ticle films were monitored with a UV-vis spectrometer as the films come in contact with a host analyte of varying concentrations. The gold particle fi lms were prepared via a sputtering and annealing method and were secured in a now cell with enough stability to remain intact while analytes now throu gh the cell. Time scans are performed as pure water is passed over the film with plugs of phenol systematically introduced for quantitation. With incr easing host concentration surrounding the film, a characteristic red-shift and increase in intensity is observed as expected from Drude theory and the Clausius-Mossotti equation for small metal particle polarizability. The re versible response was evaluated by baseline-peak extinction difference (Del ta C-ext) and integrated peak area. In both methods of analysis, a linear a greement in Delta C-ext is found in the 5 mM-0.4 M range. Gold particle fil ms modified with octanethiol exhibit the same linearity in this range. Howe ver, the normalized Delta C-ext is noticably enhanced.