Structure and Photodissociation Spectra of Mixed Ethene-Acetone Clusters

Infrared photodissociation spectra of the mixed complexes C2H4-CH3COCH3 and C2H4-(CH3COCH3)2 have been observed after size selecting them by scattering from a helium beam combined with mass spectrometric detection. The excitation of the v7-out of plane symmetric wagging mode of ethene near its gas phase frequency at 949.3 cm-1 with a cw-CO2 laser leads to a characteristic depletion of the cluster beam. The dissociation spectrum of the 1:1 complex can be explained by two peaks at 950.8 and 961.6 cm-1. Calculations of minimum energy configurations and band shifts based on an empirical site-site potential show that these frequencies can be attributed to the absorption of two different isomers. They correspond to the two different binding patterns of the H atoms of ethene to the O atom of acetone and those of acetone to the C-C group of ethene, respectively. For the 1:2 complex, a large peak at 958.5 cm-1 and a smaller onearound 940.5 cm-1 are found which can be explained in a similar manner by several isomers found in the structure calculations

Highly Charged Ions in Rare Earth Permanent Magnet Penning Traps

A newly constructed apparatus at the National Institute of Standards and Technology (NIST) is designed for the isolation, manipulation, and study of highly charged ions. Highly charged ions are produced in the NIST electron-beam ion trap (EBIT), extracted through a beamline that selects a single mass/charge species, then captured in a compact Penning trap. The magnetic field of the trap is generated by cylindrical NdFeB permanent magnets integrated into its electrodes. In a room-temperature prototype trap with a single NdFeB magnet, species including Ne10+ and N7+ were confined with storage times of order 1 second, showing the potential of this setup for manipulation and spectroscopy of highly charged ions in a controlled environment. Ion capture has since been demonstrated with similar storage times in a more-elaborate Penning trap that integrates two coaxial NdFeB magnets for improved B-field homogeneity. Ongoing experiments utilize a second-generation apparatus that incorporates this two-magnet Penning trap along with a fast time-of-flight MCP detector capable of resolving the charge-state evolution of trapped ions. Holes in the two-magnet Penning trap ring electrode allow for optical and atomic beam access. Possible applications include spectroscopic studies of one-electron ions in Rydberg states, as well as highly charged ions of interest in atomic physics, metrology, astrophysics, and plasma diagnostics.Comment: Proceedings of CDAMOP-2011, 13-16 Dec 2011, Delhi, India. To be published by Springer Verla

Photodissoziation und Photoionization von Molekuelclustern

Excitation and dissociation dynamics of size selected mixed ethylene-acetone clusters, generated by adiabatic jet stream expansion, were studied using CO_2 laser infrared radiation. Vibrational predissociation spectra are compared with theoretical interaction potentials. By integration of a second CO_2 laser in a double resonance equipment, the dissociation spectra could be resolved allowing the identification of structural isomers of identical cluster size. This method has been applied to dimers and trimers of methanol and to size selected hexameric methanol clusters and ethylene-acetone dimers. In the second part of this work a new nonmagnetic time-of-flight mass specrometer with improved resolution is described. Using this massreflection the UV photodissociation of H_2S and the mass spectra of Ar clusters ionized by laser-induced photoelectrons have been characterized. (WEN)SIGLEAvailable from TIB Hannover: RA 1396(1994,20) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Ground state potentials of the NaK molecule

We present a simultaneous analysis of the X\, ^1\Sigma^+ \,and the a\, ^3\Sigma^+ \,electronic ground states of the NaK molecule. Excitation of the [B\, ^1\Pi, c\, ^3\Sigma^+ \,]-system made it possible to record fluorescence to rovibrational levels of both ground states simultaneously with a Fourier-transform spectrometer. For the first time high lying levels in the triplet state with v = 17 and v = 18 were seen, the highest possible v = 19 for 23Na–39K was not observed. The joint evaluation of the retrieved data leads to accurate potential energy curves, that describe the experimental data within their experimental uncertainty of 0.005 cm-1. Cold collision properties like scattering length and Feshbach resonance positions are calculated with these potentials and compared to other predictions

DC-sputtering of yttria-stabilised zirconia films for solid oxide fuel cell applications

Yttria-stabilised zirconia (YSZ) thin films were dc-sputtered and investigated with respect to surface morphology, microstructure and film-substrate interface interaction. The films were deposited under argon/oxygen atmospheres on NiO/YSZ substrates heated to between 500 and 700 degreesC. Dense and crack-free coatings were obtained in the thickness range of 1 to 10 mum. The film morphology varied from columnar to crystalline structure depending on the oxygen pressure and the substrate temperature. Whereas the coated films consisted of YSZ with cubic and tetragonal crystal structure under low oxygen atmospheres, the same deposition experiments on Al2O3 substrates revealed highly disordered layers of cubic YSZ. The formation of oxide layers on the NiO/YSZ substrates is due to a film-substrate redox interaction. The NO grains close to the coating interface are partially reduced and serve as an oxygen source for the oxidation of the film. An exponential decay of the gas leakage vs. coating thickness was found. (C) 2001 Elsevier Science Ltd. All rights reserved