Unoccupied electronic structure and relaxation dynamics of Pb/Si(1 1 1)

Sandhofer, Mathias; Sklyadneva, I. Yu.; Sharma, Vandana; Trontl, Vesna Mikšić; Zhou, Ping; Ligges, Manuel; Heid, R.; Bohnen, K.‐P.; Chulkov, Evgueni V.; Bovensiepen, Uwe

doi:10.1016/j.elspec.2014.04.006

Cited by 15 publications

(6 citation statements)

References 35 publications

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“…Femtosecond laser pulses at a 1.55 eV photon energy and 40 fs pulse duration are generated in a commercial Ti/sapphire amplifier (Coherent RegA 9040) and frequency doubled in BaB 2 O 4 to ℏω = 3.10 eV. For details of the experimental setup, see ref . From the measured E kin , we calculate the energy with respect to the energy reference E F E − E F = E normalk normali normaln + Φ − 2 ℏ ω with the work function Φ, which is determined from the highest kinetic energy in the 2PPE spectrum by E kin max = 2ℏω – Φ.…”

Section: Methodsmentioning

confidence: 99%

Femtosecond Electron-Transfer Dynamics across the D₂O/Cs⁺/Cu(111) Interface: The Impact of Hydrogen Bonding

Thomas,

Patwari,

Langguth

et al. 2023

J. Phys. Chem. C

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Hydrogen bonding is essential in electron-transfer processes at water−electrode interfaces. We study the impact of the H-bonding of water as a solvent molecule on real-time electron-transfer dynamics across a Cs + −Cu(111) ion−metal interface using femtosecond time-resolved two-photon photoelectron spectroscopy. We distinguish in the formed water−alkali aggregates two regimes below and above two water molecules per ion. Upon crossing the boundary of these regimes, the lifetime of the excess electron localized transiently at the Cs + ion increases from 40 to 60 fs, which indicates a reduced alkali−metal interaction. Furthermore, the energy transferred to a dynamic structural rearrangement due to hydration is reduced from 0.3 to 0.2 eV concomitantly. These effects are a consequence of H-bonding in the water−water interaction and the beginning formation of a nanoscale water network. This finding is supported by real-space imaging of the solvatomers and vibrational frequency shifts of the OH stretching and bending modes calculated for these specific interfaces.

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Section: Methodsmentioning

confidence: 99%

Femtosecond Electron-Transfer Dynamics across the D₂O/Cs⁺/Cu(111) Interface: The Impact of Hydrogen Bonding

Thomas,

Patwari,

Langguth

et al. 2023

J. Phys. Chem. C

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“…These are energies where the electronic density of states is high and/or where the excited electrons are long-lived. For a correct prediction of the energetic position of the QWS, the (1×1) periodicity of a free-standing Pb(111) films is not sufficiently accurate [31]. It is required to take the larger ( ) 3 3 periodicity enforced by the Si(111) substrate into account.…”

Section: Theorymentioning

confidence: 99%

Relaxation of electrons in quantum-confined states in Pb/Si(111) thin films from master equation with first-principles-derived rates

Kratzer

Zahedifar

2019

New J. Phys.

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Atomically thin films of Pb on Si(111) provide an experimentally tunable system comprising a highly structured electronic density of states. The lifetime of excited electrons in these states is limited by both electron-electron (e-e) and electron-phonon (e-ph) scattering. We employ the description by a master equation for the electronic occupation numbers to analyze the relative importance of both scattering mechanisms. The electronic and phononic band structures, as well as the matrix elements for electron-phonon coupling within deformation potential theory were obtained from density functional calculations, thus taking into account quantum confinement effects. For the relaxation dynamics, the contribution of impact ionization processes to the lifetime is estimated from the imaginary part of the electronic self-energy calculated in the GW approximation. By numerically solving rate equations for the occupations of the Pb-derived electronic states coupled to a phononic heat bath, we are able to follow the distribution of the electronic excitation energy to the various modes of Pb lattice vibrations. While e-e scattering is the dominant relaxation mechanism, we demonstrate that the e-ph scattering is highly phonon-mode-specific, with a large contribution from surface phonons. At electron energies of about 0.3 eV above the Fermi surface, a 'phonon bottleneck' characteristic of relaxation in nanostructures with well-separated electronic states is observed. The time scales extracted from the simulations are compared to data from pump-probe experiments using time-resolved two-photon photoemission.

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“…Having established a good agreement between calculated and experimental cluster structures, we turn now to the electronic structure. Experimentally, this was studied by 2PPE, for which we employ femtosecond laser pulses of photon energy hω=3.1 eV [33,43]. In 2PPE, the first photon hω excites resonant electron transfer from Cu(111) to the unoccupied Cs 6s state.…”

mentioning

confidence: 99%

“…In 2PPE, the first photon hω excites resonant electron transfer from Cu(111) to the unoccupied Cs 6s state. A second photon generates the photoelectron analyzed in a spectrometer [43], see Fig. 3(a).…”

mentioning

confidence: 99%

Hydration at highly crowded interfaces

Penschke¹,

Thomas²,

Bertram³

et al. 2022

Preprint

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Understanding the molecular and electronic structure of electrolytes at interfaces requires an analysis of the interactions between the electrode surface, the ions, and the solvent environment on equal footing. Here, we tackle this challenge by exploring the initial stages of Cs + hydration on a Cu(111) surface by combining experiment and theory. Remarkably, we observe "inside out" solvation of Cs ions, i.e, their preferential location at the perimeter of the water clusters on the metal surface. In addition, water-Cs complexes containing multiple Cs + ions are observed to form at these surfaces. Established models based on maximum ion-water coordination and the double layer notion cannot account for this situation and the complex interplay of microscopic interactions is the key to a fundamental understanding.

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Unoccupied electronic structure and relaxation dynamics of Pb/Si(1 1 1)

Cited by 15 publications

References 35 publications

Femtosecond Electron-Transfer Dynamics across the D₂O/Cs⁺/Cu(111) Interface: The Impact of Hydrogen Bonding

Femtosecond Electron-Transfer Dynamics across the D₂O/Cs⁺/Cu(111) Interface: The Impact of Hydrogen Bonding

Relaxation of electrons in quantum-confined states in Pb/Si(111) thin films from master equation with first-principles-derived rates

Hydration at highly crowded interfaces

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Unoccupied electronic structure and relaxation dynamics of Pb/Si(1 1 1)

Cited by 15 publications

References 35 publications

Femtosecond Electron-Transfer Dynamics across the D2O/Cs+/Cu(111) Interface: The Impact of Hydrogen Bonding

Femtosecond Electron-Transfer Dynamics across the D2O/Cs+/Cu(111) Interface: The Impact of Hydrogen Bonding

Relaxation of electrons in quantum-confined states in Pb/Si(111) thin films from master equation with first-principles-derived rates

Hydration at highly crowded interfaces

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Product

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Femtosecond Electron-Transfer Dynamics across the D₂O/Cs⁺/Cu(111) Interface: The Impact of Hydrogen Bonding

Femtosecond Electron-Transfer Dynamics across the D₂O/Cs⁺/Cu(111) Interface: The Impact of Hydrogen Bonding