Atomic force microscopy of Au deposition from aqueous HF onto Si(111)

Non-contact atomic force microscopy (AFM) was employed following emersion t o examine Au nanoclusters deposited from aqueous mixtures of HF and 10(-4) M KAu(CN)(2) onto Si(111). As the HF concentration is increased, the growth rates both parallel and perpendicular to the substrate of the approximatel y oblate Au hemispheroids increase. AFM images were obtained for times at w hich previously reported in situ second harmonic generation signals from th e interface reach a maximum. At the time when the second harmonic enhanceme nt is maximized during deposition from 0.500 (5.00)M HF, the Au nanocluster s have an average diameter of 94 (109) nm and an average height of 3.6 (9.5 ) nm. These cluster diameters can be understood qualitatively by the shift of the plasmon resonance due to depolarization as the cluster size increase s, causing the resonant second harmonic enhancement at 532 nm to pass throu gh a maximum at cluster diameters in the range 90-110 nm. (C) 1999 Publishe d by Elsevier Science B.V. All rights reserved.