Spectral properties of the surface plasmon resonance and electron injection from gold nanoparticles to TiO2 mesoporous film: femtosecond study

Abstract

Transient absorption spectra of gold nanoparticles (AuNPs) embedded in mesoporous TiO2 film were studied by a femtosecond laser photolysis pump-probe technique using 25 fs pulses at 740 nm (1.68 eV) and a low fluence of 24 μJ cm(-2). The shift of the bleaching peak in transient spectra by ∼100 meV is detected in the AuNP-TiO2 system, whereas the bleaching peak shift of the same AuNPs in aqueous colloids is not more than ∼5 meV. In addition to the thermal mechanism of the nonlinear response of AuNPs connecting with the electron gas heating and the smearing effect of the Fermi distribution, the electron transfer between AuNPs and TiO2 becomes important for the nonlinear response, in addition to the electron heating mechanism. The electron transfer can explain both the spectral shift and widening of the SPR band of AuNPs in TiO2.

Pulse heating of water at the surface of gold nanoparticles: Femtosecond laser spectroscopy of energy relaxation of aqueous colloid of plasmonic nanoparticles under strong excitation conditions

“…4, the effect of electron-lattice relaxation slowing down with an increase in the excitation energy is also seen. The effect of decline in the electron-lattice relaxation rate is consistent with the existing concepts of plasmon relaxation [11]. Since the heat capacity of the electron gas at low excitation is approximately three orders of magnitude below that of the lattice, the nanoparticle is insignificantly heated by low excitation.…”

Operational Conditions Affecting Hydrogen Production by the Photoreforming of Organic Compounds using Titania Nanoparticles with Gold

“…[146,147] In this state,e lectronsa re transferred from surface-plasmon-stimulatedA uN Ps to the conduction band of TiO 2 . [148][149][150] Thef low of electrons is different underU Vl ight. Here, the Au loadingo nasemiconductor surface under UV light acts as an electron sink, which shows the movement of the Fermi level towards am ore negative direction, at approximately À0.27 eV,between the bottom of the TiO 2 conduction band and the H + /H 2 redox couple, [139] which is ak ey factor for increasing the Schottky barrier effect.…”

“…In recent years, catalysis and photocatalysis processes in which Au NPs are used have become popular because of their effectiveness in the degradation and mineralization of organic compounds because they are comparatively cheaper than Pt and because their inherent plasmonic oscillation makes them photoactive in the visible region, which depends upon the particle size, morphology, and dielectric constant of the medium . In this state, electrons are transferred from surface‐plasmon‐stimulated Au NPs to the conduction band of TiO 2 …”

Hydrated Electron Generation by Excitation of Copper Localized Surface Plasmon Resonance

“…In the case of NPs, the heating of the electron gas (LSPR excitation) leads to spectral broadening of the surface plasmon absorption, 30,37,38 resulting in transient bleaching at the center of the plasmon band maximum and two positive absorption wings at lower and higher energies (known as "winglets") in the diff erence spectrum. 30,38,39 Figure 3A shows the two-dimensional color map of the temporal evolution of the surface plasmon resonance of Cu excited at 398 nm, i.e., excitation at the maximum of the LSPR absorption band. The transient signal shows the expected "bleaching" of the LSPR absorption band and a winglet band (positive transient absorption signal) centered at 480 nm.…”

“…The transient signal shows the expected "bleaching" of the LSPR absorption band and a winglet band (positive transient absorption signal) centered at 480 nm. 30,38,39 The winglet band at higher energies (i.e., shorter wavelength) was not observable due to the limited wavelength range of the probe light.…”