Journal ArticleDOI
Cavity ring-down spectrometer for measuring the optical response of supported size-selected clusters and surface defects in ultrahigh vacuum
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A cavity ring-down spectrometer designed to investigate optical properties of size-selected clusters on surfaces under ultrahigh vacuum (UHV) conditions is presented in this paper, where the size of the deposition area can be controlled by means of a focusing octopole.Abstract:
A cavity ring-down spectrometer designed to investigate optical properties of size-selected clusters on surfaces under ultrahigh vacuum (UHV) conditions is presented. Clusters are produced using a laser vaporization cluster source with typical size-selected cluster currents of about 100 pA. The size of the deposition area can be controlled by means of a focusing octopole. Using the UHV compatible mirror exchanger, it is possible to have up to ten ring-down cavities and to adjust them while in vacuum. With ten cavities it is possible to cover a continuous spectral range as broad as 600 nm. The sensitivity of the method is shown to be about 5 ppm, which is two orders of magnitude better than commercial techniques. The optical spectra of small NiN clusters (N=7, 10, and 20) supported at amorphous SiO2 in the range between 417 and 669 nm are presented. Simple Mie theory calculations and oscillator-strength sum rule are in good agreement with the experimental data. The method proved to be sensitive enough for ...read more
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Soft- and reactive landing of ions onto surfaces: Concepts and applications
TL;DR: A review of the existing applications of ion soft- and reactive landing and the physical phenomena that occur during and after ion soft landing, including retention and reduction of ionic charge along with factors that impact the efficiency of ion deposition.
Journal ArticleDOI
Plasmons in supported size-selected silver nanoclusters
Tobias Lünskens,Philipp Heister,Martin Thämer,Constantin A. Walenta,Aras Kartouzian,Ulrich Heiz +5 more
TL;DR: The plasmonic behavior of size-selected supported silver clusters is studied by surface second harmonic generation spectroscopy for the first time and results are in quantitative agreement with a hybrid theoretical model based on Mie theory and the existing DFT calculations.
Journal ArticleDOI
In situ reactivity and TOF-SIMS analysis of surfaces prepared by soft and reactive landing of mass-selected ions.
TL;DR: It is demonstrated that the new instrument enables detailed studies of the reactivity of catalytically active species immobilized by soft and reactive landing toward gaseous reagents and is characterized by greater sensitivity, larger dynamic range, less fragmentation, and fewer in-plume reactions than the corresponding FTICR-SIMS spectra.
Journal ArticleDOI
Toward Control of Gold Cluster Aggregation on TiO2 via Surface Treatments
Jan-Yves Ruzicka,Faridah Abu Bakar,Faridah Abu Bakar,Christoffer Hoeck,Christoffer Hoeck,Rohul H. Adnan,Rohul H. Adnan,Campbell McNicoll,Campbell McNicoll,Campbell McNicoll,Tim Kemmitt,Tim Kemmitt,Bruce C. C. Cowie,Gregory F. Metha,Gunther G. Andersson,Vladimir B. Golovko,Vladimir B. Golovko +16 more
TL;DR: In this article, triphenylphosphine-protected Au9 clusters on TiO2 (Aeroxide P-25) were pre-treated in eight different ways and subsequently exposed to two post-treatments.
Journal ArticleDOI
Mass-Selective Chiral Analysis
Ulrich Boesl,Aras Kartouzian +1 more
TL;DR: Among the many important applications of mass-selective chiral analysis, this review focuses on its use as an analytical tool for the development of heterogeneous enantioselective chemical catalysis.
References
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Journal ArticleDOI
The physics of simple metal clusters: experimental aspects and simple models
TL;DR: In this paper, a broad range of experiments are reviewed and compared with theory, including the behavior of the mass-abundance spectra, polarizabilities, ionization potentials, photoelectron spectra and optical spectra.
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The physics of simple metal clusters: self-consistent jellium model and semiclassical approaches
TL;DR: In this article, the authors survey the hierarchy of theoretical approximations leading to the jellium model, including various extensions, including local density approximation to exchange and correlation effects, which greatly simplifies self-consistent calculations of the electronic structure.
Journal ArticleDOI
When Gold Is Not Noble: Nanoscale Gold Catalysts
A. Sanchez,Stéphane Abbet,Ueli Heiz,Wolf-Dieter Schneider,Hannu Häkkinen,Robert N. Barnett,Uzi Landman +6 more
TL;DR: In this article, temperature-programmed reaction studies of the catalyzed combustion of CO on size-selected small monodispersed Aun (n ≤ 20) gold clusters supported on magnesia, and first-principle simulations reveal the microscopic origins of the observed unusual catalytic activity, with Au8 being the smallest catalytically active size.
Journal ArticleDOI
Cavity ring-down spectroscopy: Experimental schemes and applications
TL;DR: Cavity ring-down (CRD) spectroscopy as mentioned in this paper is a direct absorption technique, which can be performed with pulsed or continuous light sources and has a significantly higher sensitivity than obtainable in conventional absorption Spectroscopy.