title: How persistent microbubbles shield nanoparticle productivity in laser synthesis of colloids - quantification of their volume, dwell dynamics, and gas composition.
abstract: During laser synthesis of colloids, cavitation bubbles with lifetimes in the microsecond-scale form and shield the laser pulse leading to a decrease in nanoparticle output. A second type of productivity-limiting bubble that severely affects the productivity of the process is often neglected. With lifetimes from milliseconds to seconds, these persistent bubbles are systematically studied in this work by quantifying their composition, amount, size and dwell time in liquids with different viscosities and by relating the results to the nanoparticle productivities. It is found that during synthesis in water, water splitting occurs leading to persistent bubbles consisting of hydrogen and oxygen. In glycols, hydrogen and molecular carbon species containing microbubbles are formed. These persistent microbubbles shield up to 65% of the incoming laser beam depending on the liquid as well as the laser fluence and require attention by means of reducing their dwell time in the ablation zone and enhancing the nanoparticle output by liquid flow. The highest productivities and monodisperse quality are achieved in liquids with the lowest viscosities.
authors.affiliation: Technical Chemistry I, University of Duisburg-Essen and Center for NanoIntegration Duisburg-Essen, CENIDE, Universitaetsstrasse 7, 45141 Essen, Germany. bilal.goekce@uni-due.de and Particular GmbH, Industriestrasse 1, 30855 Langenhagen, Germany.
authors.forename: Mark-Robert
authors.initials: MR
authors.lastname: Kalus
authors.affiliation: Particular GmbH, Industriestrasse 1, 30855 Langenhagen, Germany.
authors.forename: Niko
authors.initials: N
authors.lastname: Bärsch
authors.affiliation: Technical Chemistry I, University of Duisburg-Essen and Center for NanoIntegration Duisburg-Essen, CENIDE, Universitaetsstrasse 7, 45141 Essen, Germany. bilal.goekce@uni-due.de.
authors.forename: René
authors.initials: R
authors.lastname: Streubel
authors.affiliation: Eurofins Umwelt West GmbH, Vorgebirgsstr. 20, 50398 Wesseling, Germany.
authors.forename: Emine
authors.initials: E
authors.lastname: Gökce
authors.affiliation: Technical Chemistry I, University of Duisburg-Essen and Center for NanoIntegration Duisburg-Essen, CENIDE, Universitaetsstrasse 7, 45141 Essen, Germany. bilal.goekce@uni-due.de.
authors.forename: Stephan
authors.identifier: http://orcid.org/0000-0002-9739-7272
authors.initials: S
authors.lastname: Barcikowski
authors.affiliation: Technical Chemistry I, University of Duisburg-Essen and Center for NanoIntegration Duisburg-Essen, CENIDE, Universitaetsstrasse 7, 45141 Essen, Germany. bilal.goekce@uni-due.de.
authors.forename: Bilal
authors.identifier: http://orcid.org/0000-0001-6368-9659
authors.initials: B
authors.lastname: Gökce