title: Optomechanics of Single Aluminum Nanodisks.
abstract: Aluminum nanostructures support tunable surface plasmon resonances and have become an alternative to gold nanoparticles. Whereas gold is the most-studied plasmonic material, aluminum has the advantage of high earth abundance and hence low cost. In addition to understanding the size and shape tunability of the plasmon resonance, the fundamental relaxation processes in aluminum nanostructures after photoexcitation must be understood to take full advantage of applications such as photocatalysis and photodetection. In this work, we investigate the relaxation following ultrafast pulsed excitation and the launching of acoustic vibrations in individual aluminum nanodisks, using single-particle transient extinction spectroscopy. We find that the transient extinction signal can be assigned to a thermal relaxation of the photoexcited electrons and phonons. The ultrafast heating-induced launching of in-plane acoustic vibrations reveals moderate binding to the glass substrate and is affected by the native aluminum oxide layer. Finally, we compare the behavior of aluminum nanodisks to that of similarly prepared and sized gold nanodisks.
authors.forename: Man-Nung
authors.identifier: 0000-0003-2570-4285
authors.initials: MN
authors.lastname: Su
authors.forename: Pratiksha D
authors.initials: PD
authors.lastname: Dongare
authors.affiliation: School of Mathematics and Statistics, University of Melbourne , Melbourne, Victoria 3010, Australia.
authors.forename: Debadi
authors.initials: D
authors.lastname: Chakraborty
authors.forename: Yue
authors.initials: Y
authors.lastname: Zhang
authors.forename: Chongyue
authors.initials: C
authors.lastname: Yi
authors.forename: Fangfang
authors.initials: F
authors.lastname: Wen
authors.forename: Wei-Shun
authors.identifier: 0000-0002-0251-4449
authors.initials: WS
authors.lastname: Chang
authors.forename: Peter
authors.identifier: 0000-0002-1633-2937
authors.initials: P
authors.lastname: Nordlander
authors.affiliation: School of Mathematics and Statistics, University of Melbourne , Melbourne, Victoria 3010, Australia.
authors.forename: John E
authors.initials: JE
authors.lastname: Sader
authors.forename: Naomi J
authors.identifier: 0000-0002-8461-8494
authors.initials: NJ
authors.lastname: Halas
authors.forename: Stephan
authors.initials: S
authors.lastname: Link
keywords: Acoustic vibrations; aluminum nanostructures; nanomechanics; single-particle spectroscopy; ultrafast spectroscopy