title: Study on metal nanoparticles synthesis and orientation of gemini surfactant molecules used as stabilizer.
abstract: In the present study, we report the synthesis of gold (Au), silver (Ag), and gold-silver alloy (Au-Ag) nanoparticles (NPs) by seed-mediated method using gemini surfactant, containing diethyl ether spacer group as a stabilizer. As-synthesized NPs are found very much stable and have been characterized using UV-vis spectroscopy, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), and zeta potential techniques. The orientation of gemini surfactant molecules surrounding the metal NPs has been investigated exploiting twisted intramolecular charge transfer (TICT) fluorescence properties of a probe 4-(N,N-dimethylamino) cinnamaldehyde (DMACA). The quenching efficiencies of different NPs have been performed in the fluorescence of DMACA and are found to be different. This effect can be related to the location of DMACA as well as the electro-negativity of the metals as the extent of orientation of the surfactant molecules around NPs controls the location of DMACA in a bilayer. To support the location of DMACA, fluorescence quenching studies with cetylpyridinium chloride (CPC) as an external quencher have also been carried out.
authors.affiliation: Department of Chemistry, Birla Institute of Technology and Science, Pilani 333 031, Rajasthan, India.
authors.forename: Amit Kumar
authors.initials: AK
authors.lastname: Tiwari
authors.affiliation: Department of Physics, Birla Institute of Technology and Science, Pilani 333 031, Rajasthan, India.
authors.forename: Subhashis
authors.initials: S
authors.lastname: Gangopadhyay
authors.affiliation: Department of Chemical Engineering, National Cheng Kung University, 701 Tainan City, Taiwan.
authors.forename: Chien-Hsiang
authors.initials: CH
authors.lastname: Chang
authors.affiliation: Department of Chemistry, Birla Institute of Technology and Science, Pilani 333 031, Rajasthan, India. Electronic address: spande@pilani.bits-pilani.ac.in.
authors.forename: Surojit
authors.initials: S
authors.lastname: Pande
authors.affiliation: Department of Chemistry, Birla Institute of Technology and Science, Pilani 333 031, Rajasthan, India. Electronic address: sksaha@pilani.bits-pilani.ac.in.
authors.forename: Subit Kumar
authors.initials: SK
authors.lastname: Saha
keywords: Fluorescence quenching; Mono- and bimetallic nanoparticles; Orientation; Zeta-potential