| Autor: |
Yousefalizadeh G; Department of Chemistry, Queen's University, 90 Bader Lane, Kingston, Ontario K7L 3N6, Canada. kevin.stamplecoskie@queensu.ca., Ahmadi S, Mosey NJ, Stamplecoskie KG |
| Jazyk: |
angličtina |
| Zdroj: |
Nanoscale [Nanoscale] 2021 Jan 07; Vol. 13 (1), pp. 242-252. Date of Electronic Publication: 2020 Dec 17. |
| DOI: |
10.1039/d0nr06493a |
| Abstrakt: |
Noble metal clusters have unique photophysical properties, especially as a new class of materials for multiphoton biomedical imaging. The previously studied Au 25 SR 18 exhibits "giant" two-photon absorbance cross sections. Herein, we investigate the origins of the large two photon absorption for Au 25 SR 18 , as well as 10 other Au and Ag clusters using femtosecond pump/probe transient absorption spectroscopy (fsTAS). Excited state absorbance (ESA) ubiquitous to thiolated Au and Ag clusters is used herein as an optical signature of two-photon absorbances of the 11 different Au and Ag clusters, which does not require high quantum yields of emission. The large selection of clusters, studied with a single laser system, allows us to draw conclusions on the role of the particular metal, cluster size/structure, and the effects of the ligands on the ability to absorb multiple NIR photons. The use of a laser with a 1028 nm excitation also allows us to investigate the dramatic effect of excitation wavelength and explain why laser wavelength has led to large variances in the non-linear responses reported for clusters to date. We discuss the double resonance mechanism, responsible for giant two photon absorbance cross-sections, helping match properties of metal clusters with experimental conditions for maximizing signal/response in multiphoton applications. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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