title: Evolution of light-induced vapor generation at a liquid-immersed metallic nanoparticle.
abstract: When an Au nanoparticle in a liquid medium is illuminated with resonant light of sufficient intensity, a nanometer scale envelope of vapor-a "nanobubble"-surrounding the particle, is formed. This is the nanoscale onset of the well-known process of liquid boiling, occurring at a single nanoparticle nucleation site, resulting from the photothermal response of the nanoparticle. Here we examine bubble formation at an individual metallic nanoparticle in detail. Incipient nanobubble formation is observed by monitoring the plasmon resonance shift of an individual, illuminated Au nanoparticle, when its local environment changes from liquid to vapor. The temperature on the nanoparticle surface is monitored during this process, where a dramatic temperature jump is observed as the nanoscale vapor layer thermally decouples the nanoparticle from the surrounding liquid. By increasing the intensity of the incident light or decreasing the interparticle separation, we observe the formation of micrometer-sized bubbles resulting from the coalescence of nanoparticle-"bound" vapor envelopes. These studies provide the first direct and quantitative analysis of the evolution of light-induced steam generation by nanoparticles from the nanoscale to the macroscale, a process that is of fundamental interest for a growing number of applications.
authors.affiliation: Department of Electrical and Computer Engineering, Rice University, Houston, Texas 77005, United States. zhyfang@rice.edu
authors.forename: Zheyu
authors.initials: Z
authors.lastname: Fang
authors.forename: Yu-Rong
authors.initials: YR
authors.lastname: Zhen
authors.forename: Oara
authors.initials: O
authors.lastname: Neumann
authors.forename: Albert
authors.initials: A
authors.lastname: Polman
authors.forename: F Javier
authors.initials: FJ
authors.lastname: García de Abajo
authors.forename: Peter
authors.initials: P
authors.lastname: Nordlander
authors.forename: Naomi J
authors.initials: NJ
authors.lastname: Halas
mesh_terms: D006046:Gold / Q000737:chemistry*; D006358:Hot Temperature; D007101:Immersion; D008027:Light; D053768:Metal Nanoparticles / Q000737:chemistry*; D036103:Nanotechnology; D012542:Scattering, Radiation
chemical_list: D006046:Gold