Coupled plasmons induce broadband circular dichroism in patternable films of silver nanoparticles with chiral ligands

Xavier Vidal, Won Jin Kim, Alexander Baev, Valentyna Tokar, Hongsub Jee, Mark T. Swihart, Paras N. Prasad*

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    20 Citations (Scopus)

    Abstract

    This contribution reports the chiro-optic response of as-cast and photopatterned films of silver nanoparticles capped with photothermally- cleavable chiral ligands. We demonstrate broadband circular dichroism in these nanoparticle films, which is not present in dispersions of the nanoparticles capped with the chiral ligands. Long wavelength circular dichroism is derived from coupling of the plasmonic bands of neighbouring silver nanoparticles. Furthermore, the chiral response is preserved in the microstructured film after photopatterning using direct two-photon absorption in the plasmonic band of the silver nanoparticles. Thus, both the as-cast and photopatterned films show circular dichroism from the UV wavelength of intrinsic absorption of the ligand, through the plasmon resonances of both the isolated silver nanoparticles and the interacting nanoparticles, which extend to the near IR. Density functional theory (DFT) calculations of model electronic complexes of a chiral ligand and a small metallic cluster suggest that the new chiral bands at the plasmonic resonances are derived from new chiral hybrid electronic states of the metal nanoparticle-ligand complexes.

    Original languageEnglish
    Pages (from-to)10550-10555
    Number of pages6
    JournalNanoscale
    Volume5
    Issue number21
    DOIs
    Publication statusPublished - 7 Nov 2013

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