Lifetime of electronic excitations in metal nanoparticles

Quijada, Manuel A.; Muiño, R. Dı́ez; Borisov, A.G.; Alonso, J. A.; Echenique, Pedro M.

doi:10.1088/1367-2630/12/5/053023

Cited by 22 publications

(19 citation statements)

References 28 publications

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“…21, where shorter lifetimes are found based on spherical jellium model calculations. The difference could be attributed to the definition of the QP excitation energy.…”

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confidence: 89%

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confidence: 99%

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Quasiparticle lifetimes in magnesium clusters modeled by self-consistentGWΓcalculations

Zeng

2011

Phys. Rev. B

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Quasiparticle (QP) lifetimes in magnesium clusters are calculated using many-body Green's function theory. We analyze the effect of the self-consistency of the one-particle Green's function G on the calculations and demonstrate the necessity of the implementation of such a self-consistency. Based on hot electron and hot hole lifetimes in Mg40 calculated by the GW Γ method, we find that in the low energy excitation regime, the QP lifetimes are longer than those in the free electron gas with the electron density rs = 2.66 (3s 2 of the bulk Mg) due to the lack of states available for transitions. In the high excitation energy regime, scaled lifetimes of hot electrons converge to the range of 21 to 24 fs eV 2 . Scaled lifetimes of hot holes in this regime are shorter than those of hot electrons and decrease with increasing excitation energies.

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“…21, where shorter lifetimes are found based on spherical jellium model calculations. The difference could be attributed to the definition of the QP excitation energy.…”

mentioning

confidence: 89%

mentioning

confidence: 99%

Quasiparticle lifetimes in magnesium clusters modeled by self-consistentGWΓcalculations

Zeng

2011

Phys. Rev. B

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“…This conclusion, however, does not apply to other systems in the nanoscale. Recent calculations of electron lifetimes in metal nanoparticles showed that, for particle sizes up to a few nanometers, the lifetime does not depend much on size (49,50). Still, the lifetime value is surprisingly different from the bulk limit.…”

Section: Confinement Effects In Electron Dynamicsmentioning

confidence: 99%

“…Still, the lifetime value is surprisingly different from the bulk limit. This fact can be explained in terms of the partial localization of the electron excitation in the vicinity of the surface (50).…”

Section: Confinement Effects In Electron Dynamicsmentioning

confidence: 99%

Time-dependent electron phenomena at surfaces

Muiño

Sánchez‐Portal

Silkin

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

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Femtosecond and subfemtosecond time scales typically rule electron dynamics at metal surfaces. Recent advance in experimental techniques permits now remarkable precision in the description of these processes. In particular, shorter time scales, smaller system sizes, and spin-dependent effects are current targets of interest. In this article, we use state-of-the-art theoretical methods to analyze these refined features of electron dynamics. We show that the screening of localized charges at metal surfaces is created locally in the attosecond time scale, while collective excitations transfer the perturbation to larger distances in longer time scales. We predict that the elastic width of the resonance in excited alkali adsorbates on ferromagnetic surfaces can depend on spin orientation in a counterintuitive way. Finally, we quantitatively evaluate the electron-electron and electron-phonon contributions to the electronic excited states widths in ultrathin metal layers. We conclude that confinement and spin effects are key factors in the behavior of electron dynamics at metal surfaces.lifetimes | spin effects | time-dependent phenomena C hemistry is driven by electrons. Chemical dynamics is often determined by electron dynamics, with electronically excited states frequently acting as necessary intermediate steps in chemical activity. The understanding and control of charge transfer times and electronic excitation survival times is thus a necessary step to understand, control, and design physical and chemical processes at surfaces.Dynamics of electronic excitations at metal surfaces has been widely investigated both experimentally (1-6) and theoretically (5, 7-13). As a consequence, deep understanding has been reached about the mechanisms ruling electron decay and electron charge transfer. However, recent advances in experimental tools are raising new challenges, many of them linked to shorter time scales, smaller system sizes, and/or spin effects. In this article, we present fresh results on these expanding topics, in an effort to blaze trails in electron dynamics research.At surfaces, electron excitation, charge exchange, and electron decay typically take place in the femtosecond (fs) and attosecond (as) time scales (1 as ¼ 10 −18 s, 1 fs ¼ 10 −15 s) (i.e., at times much faster than any nuclear motion). Advance in laser-based experimental techniques has carried research on this field to a new frontier, in which direct measurements of electron processes in this time scale are possible. Attosecond spectroscopy, for instance, is nowadays able to discern the individual elementary steps in photoemission from surfaces (i.e., excitation, transport, and emission) (14, 15). Access to experimental information in the attosecond scale is asking for new theoretical concepts. In particular, one of the relevant questions is how electronic excitations are created in time and how the environment reacts in such time scale. In the photocreation of localized holes in adsorbates at metallic surfaces, this question can be reformulated as...

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“…V, where we will conclude that they should be important only for cases in which "normal" mechanisms are low. Considering other possible size-dependent effects, 26,29 there could be changes of the surface density of states with size; the hot electron lifetime varies in an energy-dependent way with size; 48 we cannot exclude that the adsorption sites and states change when going to small NPs, with steps and edges becoming important. All these influences are made improbable by the finding that the dynamics of the desorption appear to be constantthis is deduced from final state energy distributions, as will be described in Sec.…”

Section: No Desorption By Nanosecond Pulsesmentioning

confidence: 99%

Case studies in surface photochemistry on metal nanoparticles

Menzel

Kim

Mulugeta

et al. 2013

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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The authors give a survey of their work on photochemical processes at silver nanoparticles carried out in Berlin in the past decade. Using well established procedures for the preparation of silver nanoparticles (Ag NPs) supported on ultrathin alumina layers on NiAl single crystals, they have investigated the photoreactions of adsorbed (NO) 2 and of Xe induced by laser pulses. The authors examined the influences of photon energy (2.3, 3.5, and 4.7 eV) and polarization, mean particle size (2-10 nm), and pulse length (5 ns and 100 fs) on yields and cross sections, and on photoreaction mechanisms. Comparison with Ag(111) was made throughout. For the NO dimer layer, the authors find general agreement with known results on bulk Ag(111) in terms of possible reactions (NO desorption and NO monomer formation as well as conversion into adsorbed N 2 O and O) and predominant mechanism (via transient negative ion formation, TNI); NO desorption is the strongest channel. However, on the NPs, the cross sections show selective enhancement in particular under conditions of excitation of the Mie plasmon due to the field enhancement caused by it, but-more weakly-also under off-resonant conditions which the authors interpret by excitation confinement in the NPs. For ns laser pulses, the desorption yield responds linearly to photon flux so that the cross sections are independent of laser fluence. Using fs laser pulses, nonlinear yield response is found under plasmon excitation which is interpreted as due to re-excitation of hot electrons in the NPs during a single laser pulse. The dynamics of the individual process, however, stay the same under almost all conditions, as indicated by constant energy distributions over translational, rotational, and vibrational energies of the desorbing NO molecules, even in the nonlinear range. Only for the highest photon energy (i.e., off-resonance) and the smallest particles, a new channel is observed with higher translational energy which is believed to proceed via transient positive ions. The branching into the various reaction channels is found to be different on Ag NPs from that on Ag(111) which is ascribed to differing enhancements for the various channels. While these results show that for a typical molecular reaction only the yields are modified on NPs, very different behavior is observed for desorption of adsorbed Xe. Here, low intensity excitation of the Mie plasmon leads to chaotic response which must be due to hot spot formation. As in this case no simple desorption mechanism (via transient negative or positive ions, or direct HOMO-LUMO excitation of the adsorbate) is expected, a direct action of the plasmon excitation is postulated. Some general conclusions are drawn from these case studies. V

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Lifetime of electronic excitations in metal nanoparticles

Cited by 22 publications

References 28 publications

Quasiparticle lifetimes in magnesium clusters modeled by self-consistentGWΓcalculations

Quasiparticle lifetimes in magnesium clusters modeled by self-consistentGWΓcalculations

Time-dependent electron phenomena at surfaces

Case studies in surface photochemistry on metal nanoparticles

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