New experimental setup for photoelectron spectroscopy on cluster anions

Cha, Chia-Yen; Ganteför, Gerd; Eberhardt, W.

doi:10.1063/1.1143397

Cited by 120 publications

(95 citation statements)

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“…Anionic clusters are mass selected from the cluster beam with a time-of-flight mass spectrometer. When the desired carbonyl cluster anion enters the time-of-flight magnetic-bottle electron spectrometer [9], an electron is detached via pump-probe spectroscopy using two unfocused femtosecond pulses. The fundamental (1.5 eV) and second harmonic of a Ti:sapphire laser have been used as pump (ϳ1 mJ, ϳ80 fs, ϳ4 mJ͞cm 2 ) and probe (ϳ0.3 mJ) pulses.…”

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Photon-Induced Thermal Desorption of CO from Small Metal-Carbonyl Clusters

et al. 2002

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Thermal CO desorption from photoexcited free metal-carbonyl clusters has been resolved in real time using two-color pump-probe photoelectron spectroscopy. Sequential energy dissipation steps between the initial photoexcitation and the final desorption event, e.g., electron relaxation and thermalization, have been resolved for Au 2 ͑CO͒ 2 and Pt 2 ͑CO͒ 5 2 . The desorption rates for the two clusters differ considerably due to the different numbers of vibrational degrees of freedom. The unimolecular CO-desorption thresholds of Au 2 ͑CO͒ 2 and Pt 2 ͑CO͒ 5 2 have been approximated by means of a statistical Rice-Ramsperger-Kassel calculation using the experimentally derived desorption rate constants. DOI: 10.1103/PhysRevLett.88.076102 PACS numbers: 68.43.Vx, 33.80.Eh, 36.40. -c, 42.65.Re Thermal desorption of a molecule from an equilibrated surface takes place due to statistical energy fluctuations among all degrees of freedom. There is a certain probability that energy is accumulated in a specific chemisorptive bond that exceeds the desorption threshold of an adsorbed molecule. As thermal desorption is a statistical process, which is usually described in terms of stochastic time evolution of the energy content of the dissociative mode [1], the desorption rate depends first of all on the desorption threshold and the total number of degrees of freedom. In isolated particles, the energy cannot simply be released to the surrounding by diffusion or heat transport as in solids. Therefore in small metal-adsorbate clusters a finite probability exists to release the energy by thermal electron emission (thermionic emission) or thermal desorption of a ligand molecule after reaching thermal equilibrium. The energy redistributes either into a particular degree of freedom, i.e., a particular electronic state having one electron less, or a dissociative final state.For photon-induced desorption processes, many dissipation steps are involved between the initial energy absorption and final ligand evaporation. Energy dissipation in photoexcited systems proceeds via electron relaxation and vibrational relaxation where the former process is usually faster than electron-vibrational coupling. Inelastic electron-electron scattering with time constants much less than 100 fs have been observed in optically excited bulk metals [2]. Similar relaxation times have also been observed for Pd and Au nanoparticles [3]. Even the smallest transition metal clusters of Pt, Pd, and Ni show electron relaxation times of about 100 fs [4,5]. Thermalization between the electronic and vibrational system is usually slower ranging to the ps regime.Transition metal-carbonyl clusters such as Pt n ͑CO͒ m 2 are excellent candidates to study photon-induced thermal desorption processes. In these clusters decarbonylation thresholds are smaller than both the electron affinity (thermionic emission threshold) and the metal-metal dissociation energy [6,7]. Besides fluorescence, evaporation of a ligand molecule should thus be the only process by which energy can be rele...

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Photon-Induced Thermal Desorption of CO from Small Metal-Carbonyl Clusters

et al. 2002

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“…using permanent magnets for creation of the inhomogeneous magnetic field region [127]. Further developments have lead to the improvement of the energy resolution, making thus the method suitable not only for electron, electron coincidence spectroscopy, but also for electron spectroscopy on mass selected clusters [128][129] and cluster anions [130][131], for Penning ionization electron spectroscopy [132] or even vibrational spectroscopy (with 6 meV FWHM energy resolution) on clusters [133]. In the past decade, "magnetic bottle" type electron spectrometers have not only been used for electron, electron coincidence spectroscopy, but also for electron, ion coincident detection, in conjunction with time-of-flight mass spectrometers [134] [135].…”

Section: Electron Electron Coincidencementioning

confidence: 99%

Coincidence spectroscopy: Past, present and perspectives

Arion

Hergenhahn

2015

Journal of Electron Spectroscopy and Related Phenomena

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Coincidence spectroscopy is a powerful spectroscopic method addressing the recording of more than one particle involved in an ionization process simultaneously. In the current manuscript, an overview of the available flavors of coincidence experiments is given, and new results on the Auger decay of CH 3 F are discussed. An outlook of possible future experiments employing the approach is also briefly discussed.

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“…A former version of this source suitable for operation at low repetition rates (< 50 Hz) is described in [28]. In the source a pulsed electric arc burns within the center of a small cube (∼ 4 × 4 × 4 cm 3 ) manufactured from boron nitride.…”

Section: Cluster Sourcementioning

confidence: 99%

“…The PACIS [26][27][28] is basically similar to the laser vaporization source, but the material is vaporized by a pulsed electric arc. It was first developed as a pulsed cluster-ion source for laser spectroscopy experiments on free clusters [26].…”

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Deposition of mass-selected cluster ions using a pulsed arc cluster-ion source

Klipp

Grass

Müller

et al. 2001

Applied Physics A: Materials Science & Processing

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Abstract.A PACIS (pulsed arc cluster-ion source) developed for high average cluster-ion currents is presented. The performance of the PACIS at different operational modes is described, and the suitability for cluster-deposition experiments is discussed in comparison with other cluster-ion sources. Maximum currents of mass-selected cluster ions of 3-6 nA of small Si The preparation of nanostructures on surfaces is one of the major tasks in technology and basic research. Applications of nanostructured surfaces are abundant and cover a wide range from heterogeneous catalysis to high-density computer memories. From the point of view of basic research, many of the properties of small three-dimensional nanostructures and two-dimensional islands on surfaces are not well understood yet. For example, there is no systematic study of the size-dependence of the electronic structure of clusters of simple metals on surfaces, although free clusters of such metals show strong variations depending on the number of delocalized electrons [1]. Concerning the chemical properties, there are first results on the size-dependence of the catalytic properties of small clusters on inert substrates [2], but there are only very few systematic studies yet (see below). The kind of research focussing on the electronic and chemical properties of monodispersed small clusters on surfaces is only at its beginning. The reason is that it is difficult to deposit clusters with a perfectly monodispersed size distribution on a surface.

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New experimental setup for photoelectron spectroscopy on cluster anions

Cited by 120 publications

References 30 publications

Photon-Induced Thermal Desorption of CO from Small Metal-Carbonyl Clusters

Photon-Induced Thermal Desorption of CO from Small Metal-Carbonyl Clusters

Coincidence spectroscopy: Past, present and perspectives

Deposition of mass-selected cluster ions using a pulsed arc cluster-ion source

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