Seunghoon Lee, Heeyeon Hwang, Wonseok Lee, Dmitri Schebarchov, Younghyun Wy, Johan Grand, Baptiste Auguié, Dae Han Wi, Emiliano Cortés, Sang Woo Han.Extinction-to-Absorption Ratio for Sensitive Determination of the Size and Dielectric Function of Gold Nanoparticles. Quantitative Imaging of Single Light-Absorbing Nanoparticles by Widefield Interferometric Photothermal Microscopy. Yu-Chien Huang, Te-Hsin Chen, Jz-Yuan Juo, Shi-Wei Chu, Chia-Lung Hsieh.This article is cited by 15 publications. Overall, this work demonstrates that combined absorption–extinction measurements provide a much richer characterization tool for metallic nanoparticles. The ratio of extinction to absorption also provides a sensitive indicator of size for many types of nanoparticles, much more reliably than any observed plasmon resonance shifts. We conclude that the absorption spectrum is in general much more sensitive to the fine details of a nanoparticle geometry, compared to the extinction spectrum. A similar analysis is carried out on silver nanocubes to demonstrate the generality of this conclusion. We are able to pinpoint faceting and roughness as the likely causes for the observed discrepancy. We consider and discuss a number of possible explanations to account for this discrepancy, including changes in the dielectric function of Ag, size polydispersity, and shape imperfections such as elongation, faceting, and roughness. We focus in particular on the quadrupolar localized plasmon resonance of silver nanospheres, which is predicted to be very prominent in the absorption spectrum but is not observed in our experiments. We show that this mismatch between theory and experiment becomes much more important when considering the absorption spectrum and can no longer be dismissed as experimental imperfections. We study in detail the canonical case of silver nanospheres, where small discrepancies between experimental and calculated extinction spectra are still common and often overlooked. Using a suite of electromagnetic modeling tools (Mie theory, T-matrix, surface integral equation methods), we show that the absorption spectrum, in contrast to extinction, is particularly sensitive to shape imperfections such as roughness, faceting, or edge rounding. We use an integrating sphere-based method to measure the combined extinction–absorption spectra of silver nanospheres and nanocubes. Here we highlight the benefits of measuring not only the extinction (the sum of absorption and scattering) but also the absorption spectrum (which excludes scattering) for routine characterization of metallic nanoparticles. Theoretical predictions such as Mie theory for spheres can then be used to infer important properties, such as particle size and concentration. This medium may have the properties of an optical waveguide.Metallic nanoparticle solutions are routinely characterized by measuring their extinction spectrum (with UV–vis spectroscopy). It is shown that the method can be applied to (biological) photochromes contained in inhomogeneous media together with absorbing, non-photochromic impurities. This medium may have the properties of an optical waveguide.ĪB - A method is presented with the aid of which the absorption spectrum of at least one of the two states of a photochrome can be calculated from experimental difference spectra. N2 - A method is presented with the aid of which the absorption spectrum of at least one of the two states of a photochrome can be calculated from experimental difference spectra. Rights: University of Groningen, Zernike Institute for Advanced Materials

T1 - Derivation of Photochrome Absorption Spectra from Absorbance Difference Measurements

Absorbance spectra