title: Gold nanoparticle superlattices as functional solids for concomitant conductivity and SERS tuning.
abstract: Mercaptosuccinic acid protected gold nanoparticles (Au@MSA) self assemble to form superlattice (SL) crystals at the air-water interface. These have been used for gas adsorption. The current-voltage (I-V) characteristics of the SL film with embedded SL crystals, obtained by four probe measurements, show Ohmic conduction. The conductance observed was proportional to the polarizability of the adsorbed gases. The current through the SL decreases on adsorption of the gas along with decrease in the SERS intensity of a probe molecule from the crystals. We rationalise our observation of the linear dependence of the conductance on the polarizability of the adsorbed gas using a simple model calculation. Variation of the conductance may be useful in designing electrical switches operating at the nanometre length scales.
authors.affiliation: DST Unit on Nanoscience (DST UNS), Department of Chemistry and Sophisticated Analytical Instrument Facility, Indian Institute of Technology, Madras, Chennai, 600 036, India.
authors.forename: Edakkattuparambil Sidharth
authors.initials: ES
authors.lastname: Shibu
authors.forename: Jobin
authors.initials: J
authors.lastname: Cyriac
authors.forename: Thalappil
authors.initials: T
authors.lastname: Pradeep
authors.forename: J
authors.initials: J
authors.lastname: Chakrabarti
mesh_terms: D003198:Computer Simulation; D004553:Electric Conductivity; D006046:Gold / Q000737:chemistry*; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D008956:Models, Chemical; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure; D010316:Particle Size; D020349:Surface Plasmon Resonance / Q000379:methods*; D013499:Surface Properties
chemical_list: D046911:Macromolecular Substances; D006046:Gold