We have employed a classical molecular dynamics simulation for the direct pick-up reaction of adsorbates by very low energy (1-60 eV) ions scattered at a surface. The system investigated is the reactive ion scattering (RIS) of Cs+ with an adsorbate on a Pt(111) surface. The ion-dipole attraction between the projectile and the physisorbed adsorbate drives the abstraction reaction, in which the i...

X-ray observations of SN 1987A in the Magel-lanic Clouds have been performed throughout the ROSAT mission, using the PSPC and the HRI detectors. We present the X-ray light curve based on all observations in the years 1991–1995. For the first time a significant increase of the X-ray flux from SN 1987A can be seen, corresponding to X–ray luminosities (0.5-2 keV) of 0.8−2.2× 10 34 erg/s about 4 – ...

The atomic mass of Li has been measured using a Penning-ion-trap mass spectrometer to be 6.015 122 795~16! u. The fractional measurement uncertainty of 62.7310 represents a 30-fold improvement over that of the accepted published value. External ion sources were used to create ions outside the cryogenic ~4 K! environment of the Penning trap and an ion-transport beamline was used to deliver ions ...

The fragmentation times corresponding to the loss of the chromophore (Cα-Cβ bond dissociation channel) after photoexcitation at 263 nm have been investigated for several small peptides containing tryptophan or tyrosine. For tryptophan-containing peptides, the aromatic chromophore is lost as an ionic fragment (m/z 130), and the fragmentation time increases with the mass of the neutral fragment. ...

The most abundant decay channels have been studied quantitatively for high-energy (60 keV/amu) cluster ions H (3) (+)(H (2))(m = 1-14) colliding with He atoms employing a recently developed multicoincidence technique for the simultaneous detection of the correlated fragments on an event-by-event basis. This allows us to identify decay reactions and their underlying decay mechanisms responsible ...

Time-of-flight secondary ion mass spectrometry and atomic force microscopy are employed to characterize a wedge-shaped crater eroded by a 40-keV C(60)(+) cluster ion beam on an organic film of Irganox 1010 doped with Irganox 3114 delta layers. From an examination of the resulting surface, the information about depth resolution, topography, and erosion rate can be obtained as a function of crate...

After a review of some theoretical formulations of the concept of total reaction cross OR, involving low energy (4 10 MeV/amu) and high energy (> GeV/amu) models, two experimental methods used for direct measurements of q, are presented, namely the "beam attenuation" and the "associated y-rays 4 a detection" nethods. Then a number of experimental results of OR in the Fermi energy range i s give...

We derive the interaction Hamiltonian of a Laguerre-Gaussian beam with a simple atomic system, under the assumption of a small spread of the center of mass wave function in comparison with the waist of the Laguerre-Gaussian beam. The center of mass motion of the atomic system is taken into account. Using the properties of regular spherical harmonics the internal and center of mass coordinates a...