Showing papers by "Michael Meyer published in 2007"
TL;DR: In this paper, the Spitzer Space Telescope was used to detect cool dust surrounding solar type stars, indicating that multiple temperature components are suggested, implying a spatial distribution of dust extending over many tens of AU.
Abstract: (abbreviated) We report detection with the Spitzer Space Telescope of cool dust surrounding solar type stars. The observations were performed as part of the Legacy Science Program, ``Formation and Evolution of Planetary Systems'' (FEPS). From the overall FEPS sample (Meyer et al. 2006) of 328 stars having ages ~0.003-3 Gyr we have selected sources with 70 um flux densities indicating excess in their spectral energy distributions above expected photospheric emission........ .....The rising spectral energy distributions towards - and perhaps beyond - 70 um imply dust temperatures T_dust 1/3 of the debris sources we find that multiple temperature components are suggested, implying a spatial distribution of dust extending over many tens of AU. Because the disks are dominated by collisional processes, the parent body (planetesimal) belts may be extended as well. Preliminary assessment of the statistics of cold debris around sun-like stars shows that ~10% of FEPS targets with masses between 0.6 and 1.8 Msun and ages between 30 Myr and 3 Gyr exhibit 70 um emission in excess of the expected photospheric flux density. We find that fractional excess amplitudes appear higher for younger stars and that there may be a trend in 70 um excess frequency with stellar mass.
213 citations
TL;DR: Two types of amorphous ice clusters, porous and compact, which exhibit characteristic differences in electron dynamics, are identified and it is shown that in both structures solvated electrons preferentially bind on the cluster surface.
Abstract: The structure of D2O clusters on a Cu(111) surface and the femtosecond dynamics of photoexcited excess electrons are investigated by low-temperature scanning tunneling microscopy and two-photon photoemission spectroscopy. Two types of amorphous ice clusters, porous and compact, which exhibit characteristic differences in electron dynamics, are identified. By titration with Xe we show that in both structures solvated electrons preferentially bind on the cluster surface.
48 citations
TL;DR: In view of lack of autonomic effects, and the lack of hypoactivity upon forebrain stimulation, the hypolocomotion induced by systemic mCPP cannot be explained by an enhanced anxiety-like state.
31 citations
TL;DR: This result indicates the decisive influence of the interference term on the asymmetry parameter beta with its dependence on the phase difference between the outgoing p and f waves.
Abstract: Partial 3d{sub 5/2} photoionization cross sections of atomic Cs and Ba as well as the asymmetry parameter {beta} of the angular distribution of the Cs 3d{sub 5/2} photoelectrons were investigated near the threshold of the 3d{sub 3/2} channel at about 750 eV and 800 eV, respectively. Strong electron correlations, in particular, the spin-orbit activated interchannel coupling between the 3d{sub 5/2} and 3d{sub 3/2} channels, govern the observed spectra. The most striking effect was found for {beta}{sub 5/2} of Cs with a dramatic increase from {beta}=1.0 to {beta}=1.5 in the energy region where the mixing between both channels causes a pronounced minimum in the partial 3d{sub 5/2} cross section. This result indicates the decisive influence of the interference term on the asymmetry parameter {beta} with its dependence on the phase difference between the outgoing p and f waves.
13 citations
TL;DR: The 1s photoionization of atomic Li was studied by photoelectron spectroscopy in the photon energy region between 85 and 140 eV for the ground state and the three lowest excited configurations Li(*) 1s(2)nl, nl=2p, 3s, 3p to find the importance of electron correlations.
Abstract: The 1s photoionization of atomic Li was studied by photoelectron spectroscopy in the photon energy region between 85 and 140 eV for the ground state and the three lowest excited configurations Li* 1s{sup 2}nl, nl=2p, 3s, 3p. The importance of electron correlations was investigated by comparing the multielectron transitions, so-called shake-up and conjugate shake-up satellites, and the direct process, so-called main lines. The relative intensity of the satellites increases with the level of initial excitation of the Li atom. The shake-up process dominates for states with an n=3 valence electron and the satellites become stronger than the main lines. This spectacular effect can be explained by the spatial overlap of the initial and final state wave functions. Surprisingly, the spatial overlap affects shake-up and conjugate shake-up lines in the same way.
10 citations