125 research outputs found
Inside Cover: Gas-Phase Vibrational Spectroscopy of the Aluminum Oxide Anions (Al<sub>2</sub>O<sub>3</sub>)<sub>1-6</sub>AlO<sub>2</sub><sup>-</sup>
No full textThe Inside Cover picture illustrates the structures of aluminium oxide anions, which are studied in the gas phase using cryogenic ion-trap vibrational spectroscopy in combination with density functional theory. More information can be found in the Communication by K. R. Asmis, J. Sauer, and co-workers on page 868 in Issue 8, 201
Inside Back Cover: Structure and Fluxionality of B<sub>13</sub><sup>+</sup> Probed by Infrared Photodissociation Spectroscopy
No full textThe magic number boron cluster B13+ previously termed as a “molecular Wankel motor”, is predicted to exhibit an exceptional fluxionality already at low temperatures. In their Communication on page 505 ff., K. R. Asmis et al. spectroscopically confirm the structural assignment to a planar boron double wheel species and present the first experimental evidence for the quasi-rotation of the inner B3-ring using cryogenic ion vibrational spectroscopy of B13+ combined with density functional theory computations and Born–Oppenheimer molecular dynamics simulations
Mass-selected infrared photodissociation spectroscopy of v4o10+
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98936.pdf (Publisher’s version ) (Open Access
Kinetic study of the reaction of vanadium and vanadium-titanium oxide cluster anions with SO2
No full textThe reactivity of mass-selected V4O10- cluster anions towards sulphur dioxide is investigated in an ion trap under multi-collision conditions. Gas phase reaction kinetics are studied as a function of temperature (T-R = 150-275 K). The binding energy of SO2 to V4O10- is obtained by analyzing the experimental low pressure rate constants, employing the Lindemann energy transfer model for association reactions in conjunction with statistical RRKM theory. In addition, infrared multiple photon dissociation spectroscopy is used in conjunction with density functional theory for the structural assignment of the [V4O10-, SO2] complex, revealing a square pyramidal structure with the SO2 molecule incorporated in the vanadium oxide framework. Energy profiles are calculated for the reaction between V4O10- and V6O15- with SO2. Whereas the transition structures along the reaction pathway of V4O10- with SO2 have energies below those of the separated partners, the reaction of V6O15- with SO2 proceeds via a transition structure with energy higher than the educts. The role of cluster size and composition is investigated by studying the reaction kinetics of larger (V6O15- and V8O20-) and titanium doped (V3TiO10- and V2Ti2O10-) vanadium oxide clusters with SO2. The observed cluster size and composition dependencies are discussed
Infrared spectroscopy of hydrated sulfate dianions
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98838.pdf (Publisher’s version ) (Open Access
Gas phase infrared spectroscopy of mono- and divanadium oxide cluster cations
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98883.pdf (Publisher’s version ) (Open Access
Probing The Vibrational Wave Packet Dynamics On The Electronic Ground State Of Neutral Silver Tetramer: Vibrational Frequencies, Anharmonicities And Anisotropy
No full textSmall silver clusters possess remarkable luminescence and photoelectric properties, making them subject of current research.\footnote{Grandjean, D. et al. Science 2018, 361, 686–690.}
However, obtaining vibrations on small, neutral silver clusters remain challenging, due to difficulties in mass-selecting neutral clusters and a lack of easily accessible and widely wavelength-tunable far infrared light sources.
Here, we report our study on experimentally probing the vibrational wave packet dynamics on the ground state potential energy surface of the neutral silver tetramer Ag, a benchmark system for small neutral metal clusters, and unambiguously assign its structure. We combine femtosecond pump-probe spectroscopy employing the NeNePo (negative-neutral-positive) excitation scheme\footnote{Wolf, S. et al., Phys. Rev.Lett. 74(21), 4177; Hess, H. et al., Eur. Phys. J. D, 16(1), 145-149.} with a cryogenic ion-trap tandem mass spectrometer. A linear polarized ultrafast pump pulse (40 fs, tunable center wavelength from 700 nm - 820 nm) is used to selectively prepare a coherent wave packet by photodetachment from thermalized (20 - 300 K) Ag anions. The wave packet dynamics on the electronic ground state are then probed using a second polarized ultrafast pulse (50 fs, centered at 400 nm), which ionizes Ag in a two-photon process. The mass-selected cation yield as a function of the delay time (0 - 60 ps) between the two laser pulses yields the fs-NeNePo spectrum. Frequency analysis with a resolution down to about 0.5 cm by using Fourier transform of transient traces reveal one prime frequency band (109.5 0.4 cm) in all conditions and four bands at 32 cm, 78 cm, 186 cm and 295 cm dependent on pump wavelengths and temperatures. These frequencies are consists with predicted fundamental vibration frequencies (\nub{1}, \nub{2}, \nub{5} and \nub{6}) and one combination (\nub{1} + \nub{2}) for rhombic D geometry of Ag. The rephrasing period of the wave packet allows determining vibrational anharmonicities. A strong dependence of the NeNePo cation signal on the polarization of ultrafast pulses is observed, revealing information on the anisotropy of the partial waves involved in the photodetachment process
Vibrational spectra of small silicon monoxide cluster cations measured by infrared multiple photon dissociation spectroscopy
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98809.pdf (Publisher’s version ) (Open Access
Mass-selective vibrational spectroscopy of vanadium oxide cluster ions
No full textA corner stone in the study of the size-dependent properties of cluster ions in the gas phase is their structural characterization. Over the last 10 years, significant progress has been in this research field because of significant advances in the gas phase vibrational spectroscopy of mass-selected ions. Using a combination of modern experimental and quantum chemical approaches, it is now in most cases possible to uniquely identify the geometric structure of cluster ions, based on the comparison of the experimental and simulated infrared spectra. In this article, we highlight the progress made in this research area by reviewing recent infrared photodissociation (IR-PD) experiments on small and medium sized (up to 30 atoms) vanadium oxide ions
Unexpected structures of aluminum oxide clusters in the gas phase
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98828.pdf (Publisher’s version ) (Closed access
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