Studies of Ultrafast Transient Absorption Spectroscopy of Gold Nanorods in an Aqueous Solution

Abstract

Herein, ultrafast transient absorption spectroscopy is performed to probe the electron transfer studies between aqueous solution and gold nanorods (Au NRs). The seed-mediated growth method is used to synthesize crystalline cylindrical Au NRs having longitudinal plasmon resonance peak maximum at 825 nm. The as-synthesized Au NRs show average width and length of ∼10 ± 2 and ∼50 ± 2 nm, respectively, with an aspect ratio in the range of ∼5. The time-resolved decay profiles have been studied in a subpicosecond resolution range using pump wavelength at 410 nm excitation and probe wavelengths from visible to near-infrared region. The plasmon dynamics studies of Au NRs depend on the electron heating phenomena, coherent acoustic phonon vibration and electronic transient behavior, i.e., electron–phonon coupling, and homogenous dephasing processes. Thus, the obtained results highlighted that the ultrafast charge transfer dynamics studies in Au NRs could play an important role to elucidate their electronic, photothermal, and optical properties for molecular imaging, photothermal therapy, and optoelectronic and light-harvesting devices.

Unveiling Electric Field Induced Ultrafast Charge Transfer Dynamics and Photoresponse Enhancement in Gold‐Interlayered Bi2Se3

“…This bleaching signal was due to the interband transitions of an excited electron to a conduction band. [33,34] The positive signal was plasmonic-induced peaks in the TA spectra of gold that correspond to longitudinal surface plasmons (LSPR) and transverse surface plasmons (TSPR) resonance. [33,34] Moreover, as the delay time increases, the plasmonic peak wavelengths shift toward shorter wavelengths, primarily due to lattice heating.…”

“…[33,34] The positive signal was plasmonic-induced peaks in the TA spectra of gold that correspond to longitudinal surface plasmons (LSPR) and transverse surface plasmons (TSPR) resonance. [33,34] Moreover, as the delay time increases, the plasmonic peak wavelengths shift toward shorter wavelengths, primarily due to lattice heating. This shift was associated with acoustic phonon vibrations triggered by the bleaching peak oscillations.…”

“…[33,35,36] Upon photoexcitation, the electrons within the Au material undergo significant heating, reaching very high temperatures (e.g., up to 1000 K, depending on the pump power). [34,35,36] This heating of the Au material resulted in the broadening of both the SPR peak and the GSB in the TA spectra. This observation aligned with earlier ultrafast studies examining the dynamics of hot carriers in metal nanoparticles situated on SiO 2 substrates.…”

Interband- and Intraband-Induced Hot Electron Transfer in Plasmonic Gold–Cerium Oxide Core–Shell Nanoparticles

“…In the Au NP sample, where HET is not possible, we observe two decay components with fast (6.5 ± 0.3 ps) and slow (240 ± 50 ps) time constants (Table S1). The fast component is attributed to carrier relaxation via e-ph coupling (τ e‑ph ), and the slow component is attributed to carrier relaxation via phonon–phonon coupling (τ ph‑ph ). − The fast component in Au@CeO 2 (3.01 ± 0.17 ps) and Au@CeO 2 /rGO (1.68 ± 0.17 ps) has a lifetime shorter than that in the Au NP sample (6.5 ± 0.3 ps) and is assigned to thermalization dynamics. Plasmon damping occurs within ∼10 fs, giving rise to a nonthermal distribution of electron–hole pairs that subsequently thermalize with the lattice via e-ph interactions …”

Plasmon resonance dynamics and enhancement effects in tris(2,2′-bipyridine)ruthenium(ii) gold nanosphere oligomers

“…56 Furthermore, simultaneous bleaching of the interband absorption can be seen at 520 nm leading to a depopulation of the d-band in the AuNS. 57,58 Future work involves detailed studies to clarify the mechanism and kinetics of interfacial electron transfer and symmetry breaking that is surmised to give rise to a surface-stabilized MLCT state that competes with luminescence deactivation pathways. 50…”