Ultrafast Electron Dynamics in Thiolate-Protected Plasmonic Gold Clusters

Size and Ligand Effect

Masoud Shabaninezhad, Abubkr Abuhagr, Naga Arjun Sakthivel, Chanaka Kumara, Amala Dass, Kyuju Kwak, Kyunglim Pyo, Dongil Lee, Guda Ramakrishna

Research output: Contribution to journalArticle

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Abstract

The influence of passivating ligands on electron-phonon relaxation dynamics of the smallest-sized gold clusters was studied using ultrafast transient absorption spectroscopy and theoretical modeling. The electron dynamics in Au279, Au329, and Au329 passivated with 4-tert-butylbenzene thiol (TBBT), phenylethane thiol (SC2Ph), and hexane thiol (SC6), respectively, were investigated. These clusters were chosen as they are the smallest gold clusters reported till-date to show plasmonic behavior. Ultrafast transient absorption measurements were also carried out on Au∼1400 (SC6) and Au∼2000 (SC6) to understand the influence of the size on electron-phonon relaxation with the same passivating ligand. The study has revealed interesting aspects on the role of ligands on electron-phonon relaxation dynamics wherein the aromatic passivating ligands, SC2Ph and TBBT, have shown smaller power dependence and broader surface plasmon bleach, indicating dampened plasmon resonance, whereas the cluster with aliphatic passivating ligands has behaved similarly to regular plasmonic gold nanoparticles. To model the effect of the ligand on the plasmonic properties of the investigated samples, free electron density correction factor of each one was calculated using the three-layered Mie theory, and the results show that SC6 interacts least with core-gold, whereas TBBT and SC2Ph have a greater effect on the surface electronic conductivity that is attributed to π-interaction of the ligand with gold. The results also shed light on unusual electron-phonon relaxation and smaller slope observed for Au329 (SC2Ph) that is ascribed to surface gold-πinteractions creating a hybrid state. In contrast, extended π-interaction is probably the reason for the plasmonic nature observed in Au279 (TBBT), even though its size is smaller when compared to Au329. In addition, the results also have shown that the electron-phonon coupling increases with an increase in the size of the cluster, and theoretical modeling has shown increased electron conductivity for larger plasmonic gold clusters.

Original languageEnglish
Pages (from-to)13344-13353
Number of pages10
JournalJournal of Physical Chemistry C
Volume123
Issue number21
DOIs
Publication statusPublished - 2019 May 30

Fingerprint

Gold
Sulfhydryl Compounds
thiols
Ligands
gold
ligands
Electrons
electrons
conductivity
Mie scattering
interactions
Hexanes
Hexane
Absorption spectroscopy
free electrons
Carrier concentration
absorption spectroscopy
slopes
Nanoparticles
nanoparticles

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Energy(all)
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films

Cite this

Shabaninezhad, M., Abuhagr, A., Sakthivel, N. A., Kumara, C., Dass, A., Kwak, K., ... Ramakrishna, G. (2019). Ultrafast Electron Dynamics in Thiolate-Protected Plasmonic Gold Clusters: Size and Ligand Effect. Journal of Physical Chemistry C, 123(21), 13344-13353. https://doi.org/10.1021/acs.jpcc.9b01739
Shabaninezhad, Masoud ; Abuhagr, Abubkr ; Sakthivel, Naga Arjun ; Kumara, Chanaka ; Dass, Amala ; Kwak, Kyuju ; Pyo, Kyunglim ; Lee, Dongil ; Ramakrishna, Guda. / Ultrafast Electron Dynamics in Thiolate-Protected Plasmonic Gold Clusters : Size and Ligand Effect. In: Journal of Physical Chemistry C. 2019 ; Vol. 123, No. 21. pp. 13344-13353.
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abstract = "The influence of passivating ligands on electron-phonon relaxation dynamics of the smallest-sized gold clusters was studied using ultrafast transient absorption spectroscopy and theoretical modeling. The electron dynamics in Au279, Au329, and Au329 passivated with 4-tert-butylbenzene thiol (TBBT), phenylethane thiol (SC2Ph), and hexane thiol (SC6), respectively, were investigated. These clusters were chosen as they are the smallest gold clusters reported till-date to show plasmonic behavior. Ultrafast transient absorption measurements were also carried out on Au∼1400 (SC6) and Au∼2000 (SC6) to understand the influence of the size on electron-phonon relaxation with the same passivating ligand. The study has revealed interesting aspects on the role of ligands on electron-phonon relaxation dynamics wherein the aromatic passivating ligands, SC2Ph and TBBT, have shown smaller power dependence and broader surface plasmon bleach, indicating dampened plasmon resonance, whereas the cluster with aliphatic passivating ligands has behaved similarly to regular plasmonic gold nanoparticles. To model the effect of the ligand on the plasmonic properties of the investigated samples, free electron density correction factor of each one was calculated using the three-layered Mie theory, and the results show that SC6 interacts least with core-gold, whereas TBBT and SC2Ph have a greater effect on the surface electronic conductivity that is attributed to π-interaction of the ligand with gold. The results also shed light on unusual electron-phonon relaxation and smaller slope observed for Au329 (SC2Ph) that is ascribed to surface gold-πinteractions creating a hybrid state. In contrast, extended π-interaction is probably the reason for the plasmonic nature observed in Au279 (TBBT), even though its size is smaller when compared to Au329. In addition, the results also have shown that the electron-phonon coupling increases with an increase in the size of the cluster, and theoretical modeling has shown increased electron conductivity for larger plasmonic gold clusters.",
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Shabaninezhad, M, Abuhagr, A, Sakthivel, NA, Kumara, C, Dass, A, Kwak, K, Pyo, K, Lee, D & Ramakrishna, G 2019, 'Ultrafast Electron Dynamics in Thiolate-Protected Plasmonic Gold Clusters: Size and Ligand Effect', Journal of Physical Chemistry C, vol. 123, no. 21, pp. 13344-13353. https://doi.org/10.1021/acs.jpcc.9b01739

Ultrafast Electron Dynamics in Thiolate-Protected Plasmonic Gold Clusters : Size and Ligand Effect. / Shabaninezhad, Masoud; Abuhagr, Abubkr; Sakthivel, Naga Arjun; Kumara, Chanaka; Dass, Amala; Kwak, Kyuju; Pyo, Kyunglim; Lee, Dongil; Ramakrishna, Guda.

In: Journal of Physical Chemistry C, Vol. 123, No. 21, 30.05.2019, p. 13344-13353.

Research output: Contribution to journalArticle

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T1 - Ultrafast Electron Dynamics in Thiolate-Protected Plasmonic Gold Clusters

T2 - Size and Ligand Effect

AU - Shabaninezhad, Masoud

AU - Abuhagr, Abubkr

AU - Sakthivel, Naga Arjun

AU - Kumara, Chanaka

AU - Dass, Amala

AU - Kwak, Kyuju

AU - Pyo, Kyunglim

AU - Lee, Dongil

AU - Ramakrishna, Guda

PY - 2019/5/30

Y1 - 2019/5/30

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