Highly tapered pentagonal bipyramidal Au microcrystals with high index faceted corrugation: Synthesis and optical properties

Gangaiah Mettela, Radha Boya, Danveer Singh, G. V.Pavan Kumar, G. U. Kulkarni

Research output: Contribution to journalArticlepeer-review

33 Scopus citations

Abstract

Focusing light at sub-wavelength region opens up interesting applications in optical sensing and imaging beyond the diffraction limit. In the past, tapered Au wires with carved gratings have been employed to achieve nanofocusing. The fabrication process however, is expensive and the obtained wires are polycrystalline with high surface roughness. A chemical synthetic method overcoming these hurdles should be an attractive alternative. Here, we report a method to chemically synthesize Au microcrystals (∼10 μm) bearing pentagonal bipyramidal morphology with surface corrugations assignable to high index planes. The method is a single step solid state synthesis at a temperature amenable to common substrates. The microcrystals are tapered at both ends forming sharp tips (∼55 nm). Individual microcrystals have been used as pick and probe SERS substrates for a dye embedded in a polymer matrix. The unique geometry of the microcrystal also enables light propagation across its length.

Original languageEnglish
Article number1793
JournalScientific Reports
Volume3
DOIs
StatePublished - 2013
Externally publishedYes

Bibliographical note

Funding Information:
The authors thank Prof. C.N.R. Rao for his constant encouragement. We thank Dr. Basavaraja S., V.I.N.L., for help in AFM measurements, Dr. L.S. Panchakarla and Dr. N. Varghese for their assistance in Raman measurements. G.U.K. thanks DST for grant (SR/ NM/NS-13/2011(G)), India, is gratefully acknowledged. Gangaiah Mettela and Radha B thank CSIR, India, for fellowship. G.V.P.K. thanks DST for Ramanujan Fellowship, DST-SERB grant (SR/S2/LOP-0007/2011) and IISER-Pune DST Nanoscience Unit grant (SR/NM/NS-42/2009).

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