AFM imaging and plasmonic detection of organic thin-films deposited on nanoantenna arrays

Paul, J. , McMeekin, S. G., De La Rue, R. M. and Johnson, N. P. (2018) AFM imaging and plasmonic detection of organic thin-films deposited on nanoantenna arrays. Sensors and Actuators A: Physical, 279, pp. 36-45. (doi: 10.1016/j.sna.2018.05.032)

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In this study, atomic force microscopy (AFM) imaging has been used to reveal the preferential deposition of organic thin-films on patterned nanoantenna array surfaces - identifying the localised formation of both monolayer and multilayer films of octadecanethiol (ODT) molecules, depending on the concentration of the solutions used. Reliable identification of this selective deposition process has been demonstrated for the first time, to our knowledge. Organic thin-films, in particular films of ODT molecules, were deposited on plasmonic resonator surfaces through a chemi-sorption process - using different solution concentrations and immersion times. The nanoantennas based on gold asymmetric-split ring resonator (A-SRR) geometries were fabricated on zinc selenide (ZnSe) substrates using electron-beam lithography and the lift-off technique. Use of the plasmonic resonant-coupling technique has enabled the detection of ODT molecules deposited from a dilute, micromolar (1 M) solution concentration - with attomole sensitivity of deposited material per A-SRR – a value that is three orders of magnitude lower in concentration than previously reported. Additionally, on resonance, the amplitude of the molecular vibrational resonance peaks is typically an order of magnitude larger than that for the non-resonant coupling. Fourier-transform infrared (FTIR) spectroscopy shows molecule specific spectral responses – with magnitudes corresponding to the different film thicknesses deposited on the resonator surfaces. The experimental results are supported by numerical simulation.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Johnson, Dr Nigel and De La Rue, Professor Richard and Paul, Dr Jharna
Authors: Paul, J., McMeekin, S. G., De La Rue, R. M., and Johnson, N. P.
College/School:College of Science and Engineering
College of Science and Engineering > School of Engineering > Electronics and Nanoscale Engineering
Journal Name:Sensors and Actuators A: Physical
ISSN (Online):0924-4247
Published Online:24 May 2018
Copyright Holders:Copyright © 2018 The Authors
First Published:First published in Sensors and Actuators A: Physical 279:36-45
Publisher Policy:Reproduced under a Creative Commons License

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
760541EPSRC-ISF 2016: Daphne Jackson Trust FellowshipMuffy CalderEngineering and Physical Sciences Research Council (EPSRC)EP/P51133X/1COM - COMPUTING SCIENCE