title: Power-law analysis of surface-plasmon-enhanced electromagnetic field dependence of blinking SERS of thiacyanine or thiacarbocyanine adsorbed on single silver nanoaggregates.
abstract: Blinking statistics in surface-enhanced Raman scattering (SERS) of thiacyanine or thiacarbocyanine adsorbed on single Ag nanoaggregates were analyzed by a power law. A power law reproduces the probability distributions of both the bright and dark SERS occurrences against their duration times. As the localized surface plasmon resonance (LSPR) wavelength of a single Ag nanoaggregate approached the excitation wavelength or the excitation laser intensity increases, the power-law exponents were close to -1.5, a value derived from a one-dimensional random walk model. When the LSPR wavelength left the excitation wavelength or the excitation laser intensity decreases, the power-law exponents deviated from -1.5. The decrease in the power-law exponents in the bright SERS, which indicates a decrease in the probabilities of the long-lived bright SERS, and the increase in the power-law exponents in the dark SERS coincide with the increasing shallowness and narrowing of a optical trapping potential well due to a surface-plasmon-enhanced electromagnetic field around a junction of the Ag nanoaggregates excited at a wavelength apart from the LSPR wavelength or under the low laser intensity, i.e., the low original electromagnetic field, respectively.
authors.affiliation: Department of Chemistry, School of Science and Technology, Kwansei Gakuin University, Sanda, Hyogo 669-1337, Japan. kitahama@kwansei.ac.jp
authors.forename: Yasutaka
authors.initials: Y
authors.lastname: Kitahama
authors.forename: Yuhei
authors.initials: Y
authors.lastname: Tanaka
authors.forename: Tamitake
authors.initials: T
authors.lastname: Itoh
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Ozaki
mesh_terms: D002232:Carbocyanines / Q000737:chemistry*; D004574:Electromagnetic Fields; D053768:Metal Nanoparticles / Q000737:chemistry*; D012834:Silver / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D013059:Spectrum Analysis, Raman
chemical_list: D002232:Carbocyanines; D012834:Silver