Ultrafast excited state dynamics and femtosecond nonlinear optical properties of laser fabricated Au and Ag50Au50 nanoparticles

Krishnakanth, K N and Chandu, Byram and Raavi, Sai Santosh Kumar and et al, . (2019) Ultrafast excited state dynamics and femtosecond nonlinear optical properties of laser fabricated Au and Ag50Au50 nanoparticles. Optical Materials, 95. p. 109239. ISSN 09253467

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Abstract

The localized surface plasmon dynamics of laser ablated gold and gold-silver alloy nanoparticles (NPs) near interband and intraband excitation wavelengths were investigated using femtosecond (fs) transient absorption spectroscopy. Interband excitation with 70 fs laser pulses at a wavelength of 400 nm demonstrated plasmon photo-bleach and a transient absorption in the wings of the bleach spectrum. With intraband excitation, Ag50Au50 alloy NPs depicted a fast electron thermalization time of ~180 fs. A slower decay of positive absorption from alloy NPs was observed when compared to pure Au NPs. These NPs demonstrated a rapid initial electron thermalization and exhibited similar electron-phonon relaxation times. The third-order nonlinear optical (NLO) properties were measured using the Z-scan technique with 1 kHz repetition rate fs pulses at 800 nm. It is observed that the alloy NPs possessed large value of the NLO susceptibility χ(3) (~10−13 esu) compared to pure gold NPs at 800 nm finding applications in different areas of photonics.

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IITH Creators:
IITH CreatorsORCiD
Raavi, Sai Santosh Kumarhttp://orcid.org/0000-0002-2496-9233
Item Type: Article
Uncontrolled Keywords: Ablation, Electron thermalization, Femtosecond, Transient absorption
Subjects: Physics
Divisions: Department of Physics
Depositing User: Team Library
Date Deposited: 22 Jul 2019 09:39
Last Modified: 22 Jul 2019 09:39
URI: http://raiith.iith.ac.in/id/eprint/5771
Publisher URL: http://doi.org/10.1016/j.optmat.2019.109239
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