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Photoexcitation
About: Photoexcitation is a research topic. Over the lifetime, 5874 publications have been published within this topic receiving 134733 citations.
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TL;DR: In this article, the polarized absorption spectra of Zn2SiO4 willemite crystals doped with Co2+ consist of three band systems in the near-infrared and visible spectra region centered at 3800, 7000, and 17000 cm−1, respectively.
45 citations
TL;DR: In this article, femtosecond X-ray scattering and emission measurements following photoinduced charge-transfer excitation in a mixed-valence bimetallic (FeiiRuiii) complex in water, and their interpretation using non-equilibrium molecular dynamics simulations.
Abstract: It is well known that the solvent plays a critical role in ultrafast electron-transfer reactions. However, solvent reorganization occurs on multiple length scales, and selectively measuring short-range solute–solvent interactions at the atomic level with femtosecond time resolution remains a challenge. Here we report femtosecond X-ray scattering and emission measurements following photoinduced charge-transfer excitation in a mixed-valence bimetallic (FeiiRuiii) complex in water, and their interpretation using non-equilibrium molecular dynamics simulations. Combined experimental and computational analysis reveals that the charge-transfer excited state has a lifetime of 62 fs and that coherent translational motions of the first solvation shell are coupled to the back electron transfer. Our molecular dynamics simulations identify that the observed coherent translational motions arise from hydrogen bonding changes between the solute and nearby water molecules upon photoexcitation, and have an amplitude of tenths of angstroms, 120–200 cm−1 frequency and ~100 fs relaxation time. This study provides an atomistic view of coherent solvent reorganization mediating ultrafast intramolecular electron transfer. Solvent plays a critical role in electron-transfer reactions, but short-range solvation dynamics are challenging to observe. Now, femtosecond X-ray solution scattering has been used to directly monitor the reorganization of water upon ultrafast intramolecular electron transfer in a bimetallic complex. Coherent motions of the first-shell water molecules are observed, arising from changes in solute–solvent hydrogen bonding.
44 citations
TL;DR: In this paper, the shape of the resonant two-photon photoelectron spectrum compared to that arising from direct (high energy) photodetachment is interpreted in terms of the vibrational state selection created in the resonance step.
44 citations
TL;DR: It has been experimentally found that upon excitation to the (2)P1/2 state, the Ag atoms are ejected with a speed distribution peaking at about 55 m s(-1), while a fraction of the impurity remains solvated and the impurities that are ejected from the droplets either as Ag or AgHe have speed distributions similar, but not identical, to those found for excitation.
Abstract: The dynamics following the photoexcitation of Ag atoms in 4He nanodroplets via the 5p 2P1/2 ← 5s 2S1/2 and 5p 2P3/2 ← 5s 2S1/2 transitions has been investigated in a joint experimental and theoretical effort. It has been experimentally found that upon excitation to the 2P1/2 state, the Ag atoms are ejected with a speed distribution peaking at about 55 m s−1. When Ag is excited to the 2P3/2 state, a rich phenomenology is found. While a fraction of the impurities remains solvated, the impurities that are ejected from the droplets either as Ag or AgHe have speed distributions similar, but not identical, to those found for excitation to the 2P1/2 state. The experimental findings are qualitatively analyzed within a three-dimensional, time-dependent density functional approach for the helium droplet. The dynamics of the Ag–4He1000 system has been followed for several tens of picoseconds, long enough to observe AgHe exciplex formation and the departure of the photoexcited Ag atom from the helium droplet.
44 citations
TL;DR: In this paper, the effect of femtosecond laser irradiation on bulk and single-layer MoS2 on silicon oxide was studied and the intensity of A1g and E2g1 vibrational modes was recorded as a function of the number of irradiation pulses.
Abstract: The effect of femtosecond laser irradiation on bulk and single-layer MoS2 on silicon oxide is studied. Optical, Field Emission Scanning Electron Microscopy (FESEM) and Raman microscopies were used to quantify the damage. The intensity of A1g and E2g1 vibrational modes was recorded as a function of the number of irradiation pulses. The observed behavior was attributed to laser-induced bond breaking and subsequent atoms removal due to electronic excitations. The single-pulse optical damage threshold was determined for the monolayer and bulk under 800nm and 1030nm pulsed laser irradiation and the role of two-photon versus one photon absorption effects is discussed.
44 citations