Two-photon photoemission from silver nanoparticles on thin alumina films: Role of plasmon excitation

Evers, Florian; Rakete, Christoph; Watanabe, Kazuo; Menzel, D.; Freund, Hans‐Joachim

doi:10.1016/j.susc.2005.06.045

Cited by 35 publications

(52 citation statements)

References 14 publications

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“…At 1=R > 0:4 nm À1 (D < 5 nm), the Landau damping saturates. The total plasmon oscillator strength decreases with the total number of atoms in the NP, i.e., with V, according to Mie theory [25] as well as experiment [16] which explains the steep drop. Finally, f settles to the value of 15 at 1=R ¼ 0:7 nm À1 , which is comparable to those without plasmon excitation and attributable to confinement.…”

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confidence: 82%

“…The optical properties and electronic structure for Ag NPs (diameters 2-12 nm) are known from photon STM [15] and two-photon photoemission spectroscopy [16] showing their ð1; 0Þ Mie plasmon resonance at $3:5-3:6 eV. NO molecules adsorbed on silver surfaces at low temperatures (below 90 K) form adsorbed dimers which are photoreactive at photon energies as low as $2 eV, qualitatively similar to Ag(111) [17][18][19].…”

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confidence: 99%

“…At 3.5 eV in p polarization, the ð1; 0Þ Mie plasmon of the Ag NPs [15,16] is excited, enhancing the surface electric field at the Ag NPs. For D > 20 nm the plasmons decay mainly by photon emission, whereas Landau damping of plasmons into single electron-hole (e-h) pairs (with the hot electrons exciting the adsorbate) becomes more efficient for decreasing D and dominant at 1 D 4 nm [23].…”

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Size Effects in Thermal and Photochemistry of(NO)2on Ag Nanoparticles

et al. 2008

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NO dimers adsorbed on alumina supported silver nanoparticles (Ag NPs, radii R approximately 1-6 nm) show decreasing desorption temperatures and complex behavior of photoinduced desorption with decreasing NP size. In particular, for resonant excitation of the (1,0) Mie plasmon at 3.5 eV the photoinduced desorption cross section increases with 1/R, showing a pronounced enhancement (40 times) at R approximately 2.5 nm compared to Ag(111). At 4.7 eV the translational temperature of photodesorbed NO increases strongly with 1/R. We discuss these trends and peculiarities in terms of the size-dependent properties of the Ag NPs.

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Size Effects in Thermal and Photochemistry of(NO)2on Ag Nanoparticles

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“…This indicates that only Xe atoms in direct contact with the Ag NPs are responsible for the hyperthermal and chaotic desorption on resonance with the (1,0) mode of the Mie plasmon (which lies at h 3:6 eV, p-polarization [17]) at low laser fluences. This suggests that the Mie plasmon plays a critical role in the hyperthermal chaotic desorption of Xe from Ag NPs.…”

Section: Prl 99 225501 (2007) P H Y S I C a L R E V I E W L E T T E mentioning

confidence: 97%

“…Ag NPs were formed by depositing Ag atoms from an electron beam evaporator on an Al 2 O 3 =NiAl110 substrate. The average size of the AgNPs was set at 8 nm as calibrated by separate STM observations [12]; their (1,0) plasmon resonance is at 3:6 eV [12,17]. The sample was coolable to 20 K by liquid helium and could be dosed with Xe gas.…”

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Hyperthermal Chaotic Photodesorption of Xenon from Alumina-Supported Silver Nanoparticles: Plasmonic Coupling and Plasmon-Induced Desorption

et al. 2007

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Excitation of Xe monolayers on alumina-supported silver nanoparticles (AgNPs) by laser light in the (1,0) Mie plasmon resonance can lead to desorption of Xe atoms with hyperthermal energy and chaotic time structure. The chaotic behavior is most likely due to plasmonic coupling between AgNPs. We argue that the desorption is induced by direct energy transfer to the adsorbate from the Pauli repulsion of the collectively oscillating electrons of the plasmon at the surface. A simple model calculation shows that this is possible. A connection between both effects appears likely. DOI: 10.1103/PhysRevLett.99.225501 PACS numbers: 61.46.Df, 68.43.Tj, 71.45.Gm, 73.20.Mf Metal nanoparticles (MNPs) in the size range 1 to 20 nm have special properties, not only in catalysis and other near ground state surface properties, but also with respect to electronic excitations and, consequently, to photoninduced surface reactions [1,2]. Important factors are the confinement of electronic and phononic excitations in the particles, which may lead to quite strong changes of their lifetimes. For MNPs containing quasifree electrons the most drastic change in the excitation spectrum is the existence of the so-called Mie plasmon [3]. These two effects can concur, leading to special properties of MNPs for photoreactions [2]. Drastic increases in photoreaction cross sections by excitation in the plasmon resonance have been observed [4 -8], with the first work [4] reporting the nonthermal evaporation of Na atoms from NaNPs in their plasmon range. However, it appears that-with the possible exception on ref.[4]-no clear indication of a unique action of the plasmon itself has been seen; all cases reported, e.g., of photodesorption, may be understood either in terms of cross section enhancement due to the plasmoninduced field enhancement without change of the nonthermal desorption mechanism [5][6][7], or by strongly enhanced thermal effects [8]. Nonthermal photodesorption usually occurs through the transient excitation of a repulsive adsorbate state. In the energy range concerned (about 2 to 4 eV) the main mechanism goes via transient negative ions (TNI mechanism): absorption of the light by the metal substrate creates hot electrons; the latter can form transient negative ions of the adsorbed species with shifted potentials which leads to momentum transfer and ultimatelyafter backtransfer of the excited electron to the substrateto desorption [9]. The events appear to be essentially the same in and off the plasmon resonance. The Mie plasmon is known to have a very short lifetime (of around 10 fs or less) [10] and partly decays into electron-hole pairs which can enter this mechanism. Besides these nonthermal processes, confinement of the large energy input into the MNPs in the plasmon resonance can also lead to strong thermal events (diffusion, shape changes, desorption), even in the MNPs themselves [11].Here we report a case of nonthermal desorption where the plasmon is not just a means to drastically increase the energy input into the MNPs, but...

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Electronically induced surface chemistry: localised bond breaking versus delocalisation

Menzel

2006

Surface & Interface Analysis

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Surface photochemistry can be considerably different from the corresponding molecular photochemistry. This is due to the fact that bonding of reactants to a surface induces modifications also in reaction paths via electronically excited states. These changes are of importance in respect of both fundamental and applied research. The past 40 years have seen the development of quite detailed understanding of the underlying effects, in particular in the case of bond breaking, which shows up by desorption of neutral and charged molecules and/or fragments. Recent developments in laser technology and nanostructuring have brought renewed interest to this field. Here a survey is given of the important facts and ideas in this realm. It will be argued that the counterplay between localisation of excitations and their delocalisation by coupling is the decisive effect to be understood.

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Two-photon photoemission from silver nanoparticles on thin alumina films: Role of plasmon excitation

Cited by 35 publications

References 14 publications

Size Effects in Thermal and Photochemistry of(NO)2on Ag Nanoparticles

Size Effects in Thermal and Photochemistry of(NO)2on Ag Nanoparticles

Hyperthermal Chaotic Photodesorption of Xenon from Alumina-Supported Silver Nanoparticles: Plasmonic Coupling and Plasmon-Induced Desorption

Electronically induced surface chemistry: localised bond breaking versus delocalisation

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