Investigation of metal cluster production with the Matrix Assembly Cluster Source and chemical deposition of gold nanoparticles in porous silicon for optical studies

Mathieu, Thibaut (2019). Investigation of metal cluster production with the Matrix Assembly Cluster Source and chemical deposition of gold nanoparticles in porous silicon for optical studies. University of Birmingham. Ph.D.

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Abstract

Firstly, we investigated a novel method in which metal clusters are formed from the sputtering of a cryogenic solidified carbon dioxide gas matrix loaded with metal atoms, dubbed the Matrix Assembly Cluster Source (MACS). Using STEM images of the deposited silver clusters on TEM grids, we studied their size-dependence as a function of both the metal loading in the dry ice matrix and the energy ofthe sputtering ion beam used to extract them. Secondly, a MACS2 system was built, which enabled the deposition of metal clusters on a larger area. Silver, gold and binary gold-palladium clusters were produced with the MACS2 and deposited on presputtered graphite tape. Flakes of graphite loaded with metal clusters were produced and it is demonstrated that these samples show catalytic activity for the carbon monoxide oxidation reaction. Finally, gold nanoparticles were chemically embedded in porous silicon layers. Reflectometry measurements were used to determine the linear refractive index and the composition of the nanocomposites in near infrared. Ultrafast time-resolved pump-probe spectroscopy measurements are carried out on the samples, using an 800 om p-polarised pump and a 2.5 J.lm s-polarised probe. Carrier densities, linear and nonlinear optical constants are determined experimentally, supported by optical models.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):