title: Metal-semiconductor pair nanoparticles by a physical route based on bipolar mixing.
abstract: In this report a methodology is described and demonstrated for preparing Au-Ge pair nanoparticles with known compositions by extending and modifying the basic steps normally used to synthesize nanoparticles in carrier gas. For the formation of pair nanoparticles by bipolar mixing, two oppositely charged aerosols of nanoparticles having the desired size are produced with the help of two differential mobility analyzers. Then both are allowed to pass through a tube, which provides sufficient residence time to result in nanoparticle pair formation due to Brownian collisions influenced by Coulomb forces. The effect of residence time on the formation of nanoparticle pairs as well as the influence of diffusion and discharging is described. Subsequently, necessary modifications to the experimental setup are demonstrated systematically. The kinetics of nanoparticles pair formation in a carrier gas is also calculated and compared with measurements made with the help of an online aerosol size analysis technique. This synthesis of nanoparticle pairs can be seen as a possible route towards Janus-type nanoparticles.
authors.affiliation: Institute of Technology for Nanostructures, Faculty of Engineering Science, and CENIDE, University of Duisburg-Essen, Duisburg, 47057, Germany. H.N.B. Garhwal University (A Central University) Srinagar (Garhwal) Uttarakhand, 246174, India.
authors.forename: Shubhra
authors.initials: S
authors.lastname: Kala
authors.forename: Ralf
authors.initials: R
authors.lastname: Theissmann
authors.forename: Marcel
authors.initials: M
authors.lastname: Rouenhoff
authors.forename: Frank Einar
authors.initials: FE
authors.lastname: Kruis