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Nanoscale Imaging and Spectroscopy of Plasmonic Modes with the PTIR technique



Aaron M. Katzenmeyer, Jungseok Chae, Richard Kasica, Glenn Holland, Basudev Lahiri, Andrea Centrone


The collective oscillation of conduction electrons in plasmonic nanomaterials allows the coupling of propagating light waves with nanoscale volumes of matter ("hot spots") and allows engineering their optical response from the UV to THz as a function of nanostructure size and shape. These properties can be leveraged for important applications such as sensing, photovoltaics, cloaking and therapeutics. For example, plasmonic nanostructures with resonances in the mid-infrared are responsible for Surface-Enhanced Infrared Absorption, increasing the chemical detection limits of IR spectroscopy up to the zeptomolar range. Despite numerous practical applications only a few experimental techniques are available to characterize plasmonic materials with high spatial resolution. For example, scattering type scanning near-field optical microscopy (s-SNOM) measures the light scattered by an atomic force microscope tip in proximity of a sample and has been successfully used to map the near-field properties of plasmonic structures. However, the limited wavelength tunability of s-SNOM sources allowed for the interrogation of plasmonic structures at only one or a few wavelengths or as a convolution of broad-band excitation. In any case, the spectrum of a plasmonic structure in the near-field has not been reported yet and theoretical calculations are typically necessary to guide experiments, extract meaningful data, and put the sparse experimental points into context. On the contrary, by measuring the near-field absorption(not scattering), the Photothermal Induced Resonance (PTIR) technique allows nanoscale resolution imaging and spectroscopy over the whole mid-IR spectral range. In this work, we apply the PTIR technique to obtain the first near-field absorption spectra of gold asymmetric split ring resonators and to image their plasmonic modes. Since the PTIR spectra are not affected by scatter
Advanced Optical Materials


plasmonics, near-field, PTIR, dark mode, Fano resonances


Katzenmeyer, A. , Chae, J. , Kasica, R. , Holland, G. , Lahiri, B. and Centrone, A. (2014), Nanoscale Imaging and Spectroscopy of Plasmonic Modes with the PTIR technique, Advanced Optical Materials, [online],, (Accessed April 19, 2024)
Created July 31, 2014, Updated October 12, 2021