Increased Refractive Index Sensitivity by Circular Dichroism Sensing through Reduced Substrate Effect

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaperJournal articleResearchpeer-review

DOI

An optical sensor based on the localized surface plasmon resonance (LSPR) of chiral Au nanohooks with increased refractive index (RI) sensitivity via circular dichroism (CD) measurements is presented. Programmed control of sample rotation combined with angled physical vapor deposition is applied to hole-mask colloidal lithography to provide in process modification of the hole-masks and generate arrays of chiral nanostructures with an adjustable optical response. Extinction spectra with unpolarized light as well as circular dichroism measurements are compared for left- and right-handed hook structures. Analysis of the LSPR peak shift of the substrate-attached nanostructures revealed the CD measurements to be twice as sensitive as the measurements with unpolarized light (304 and 146 nm RIU -1 , respectively) and close to the maximum predicted for LSPR sensing at this spectral region (∼700 nm). Finite-difference time-domain simulations with different substrate materials show that the difference in RI sensitivity can be attributed to the limiting effect of the substrate for the unpolarized extinction measurements, while CD-based sensing retains a high sensitivity, unaffected by the limiting effect of the substrate. CD-based readout could provide a complementary and improved sensitivity for substrate-bound LSPR sensor formats.

Original languageEnglish
JournalJournal of Physical Chemistry C
Volume123
Issue12
Pages (from-to)7347-7355
Number of pages9
ISSN1932-7447
DOIs
Publication statusPublished - Mar 2019

    Research areas

  • ARRAYS, ENHANCEMENT, METAMATERIALS, NANOPARTICLES, NANOSTRUCTURES, OPTICAL BIOSENSORS, SENSORS, SHAPE, SILVER, SURFACE-PLASMON RESONANCE

See relations at Aarhus University Citationformats

ID: 149029545