Kalus Mark-Robert, Bärsch Niko, Streubel René, Gökce Emine, Barcikowski Stephan, Gökce Bilal
Technical Chemistry I, University of Duisburg-Essen and Center for NanoIntegration Duisburg-Essen, CENIDE, Universitaetsstrasse 7, 45141 Essen, Germany.
Particular GmbH, Industriestrasse 1, 30855 Langenhagen, Germany.
Phys Chem Chem Phys. 2017 Mar 8;19(10):7112-7123. doi: 10.1039/c6cp07011f.
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.
在胶体的激光合成过程中，寿命处于微秒级的空化气泡形成并屏蔽激光脉冲，导致纳米颗粒产量下降。另一种严重影响该过程生产率的限制生产率的气泡类型常常被忽视。这些持续时间从毫秒到秒的气泡，在这项工作中，通过量化它们在不同粘度液体中的成分、数量、大小和停留时间，并将结果与纳米颗粒生产率相关联，对其进行了系统研究。研究发现，在水中合成时，会发生水分解，产生由氢气和氧气组成的持续气泡。在二醇中，会形成含有微气泡的氢气和分子碳物种。这些持续的微气泡根据液体、激光能量密度的不同，会屏蔽高达65%的入射激光束，需要通过减少它们在烧蚀区的停留时间以及通过液体流动提高纳米颗粒产量来加以关注。在粘度最低的液体中可实现最高的生产率和单分散质量。
