Absorption Spectroscopy of Single Optically Trapped Gold Nanorods.
Extinction spectra of single gold nanorods optically trapped in water were measured by spatial modulation spectroscopy. Comparison of the extinction cross sections and resonance frequencies to finite element calculations allows us to determine the dimensions of the nanorod and estimate the contribution of radiation damping to the LSPR line width. Subtracting the radiation damping and bulk contributions from the measured line widths yields the electron-surface scattering contribution. The results show that the surfactant coating for the nanorods causes large electron-surface scattering effects with significant particle-to-particle variations. These effects are more pronounced than those seen for substrate-supported particles in previous single particle studies. Indeed, the measured line widths are only slightly narrower than that of the ensemble spectrum. These results show the importance of removing surfactant for sensing applications of these materials.
Department of Chemistry and Biochemistry, University of Notre Dame , 251 Nieuwland Science Hall, Notre Dame, Indiana 46556-5670, United States.
Zhongming
Z
Li
Department of Chemistry and Biochemistry, University of Notre Dame , 251 Nieuwland Science Hall, Notre Dame, Indiana 46556-5670, United States.
Weizhi
W
Mao
Department of Chemistry and Biochemistry, University of Notre Dame , 251 Nieuwland Science Hall, Notre Dame, Indiana 46556-5670, United States.
Mary Sajini
MS
Devadas
Department of Chemistry and Biochemistry, University of Notre Dame , 251 Nieuwland Science Hall, Notre Dame, Indiana 46556-5670, United States.
Gregory V
GV
Hartland
Spatial modulation spectroscopy; electron−surface scattering; gold nanorods; optical trapping; single particle