Search results for "electron beam"
showing 10 items of 129 documents
Fabrication of layered nanostructures by successive electron beam induced deposition with two precursors: protective capping of metallic iron structu…
2011
We report on the stepwise generation of layered nanostructures via electron beam induced deposition (EBID) using organometallic precursor molecules in ultra-high vacuum (UHV). In a first step a metallic iron line structure was produced using iron pentacarbonyl; in a second step this nanostructure was then locally capped with a 2-3 nm thin titanium oxide-containing film fabricated from titanium tetraisopropoxide. The chemical composition of the deposited layers was analyzed by spatially resolved Auger electron spectroscopy. With spatially resolved x-ray absorption spectroscopy at the Fe L₃ edge, it was demonstrated that the thin capping layer prevents the iron structure from oxidation upon e…
Effect of the surface stoichiometry on the interaction of Mo with TiO2 (110)
2000
Abstract Molydenum has been deposited at room temperature on (110) TiO2 surfaces with different stoichiometries, roughnesses and crystallinities. Whatever the substrate preparation is, in-situ Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) studies as well as ex-situ atomic force microscopy (AFM) and reflexion high-energy electron diffraction (RHEED) studies reveal a Stranski–Krastanov growth mode: the completion of three monolayers followed by islands growth is observed in every case. The three monolayers are always composed of amorphous molybdenum oxide with an oxidation state of molybdenum less than IV. The oxidation of the molybdenum layers generates Ti3+ an…
Investigations of TiO2 films deposited by different techniques
1991
High refractive TiO2 films deposited by reactive electron beam evaporation, reactive ion plating and dip coating have been characterized by optical spectroscopy, electron spectroscopy for chemical analysis, Rutherford backscattering spectroscopy, nuclear reaction analysis and Raman spectroscopy. The spectral refractive index n exhibits a strong dependence on the deposition conditions. These findings will be connected to variations in density, stoichiometry, hydrogen content (H2O) and binding structure of the layers. A strong correlation is found between optical quantities and microscopic properties of TiO2 films.
First Fourier-transform ion cyclotron resonance signals of very highly charged atomic ions
1994
We report on the first application of Fourier-transform ion cyclotron resonance mass spectrometry to the very highly charged ions produced in the high-energy electron beam ion trap (SuperEBIT) at the Lawrence Livermore National Laboratory. Initial results are described, and spectra are presented from ions as highly charged as Cs53+.
Free-standing 2D metals from binary metal alloys
2020
Recent experiment demonstrated the formation of free-standing Au monolayers by exposing Au-Ag alloy to electron beam irradiation. Inspired by this discovery, we used semi-empirical effective medium theory simulations to investigate monolayer formation in 30 different binary metal alloys composed of late d-series metals Ni, Cu, Pd, Ag, Pt, and Au. In qualitative agreement with the experiment, we find that the beam energy required to dealloy Ag atoms from Au-Ag alloy is smaller than the energy required to break the dealloyed Au monolayer. Our simulations suggest that similar method could also be used to form Au monolayers from Au-Cu alloy and Pt monolayers from Pt-Cu, Pt-Ni, and Pt-Pd alloys.
Possible mechanism of energy storage in optically stimulable materials: doped alkali halides
1997
Radiation-induced effects in doped alkali halides, mainly in KBr:In, are studied by the luminescence technique. The activator luminescence during a 10 s under UV-light or electron irradiation and, after it, the pulsed photostimulated luminescence on a phosphorescence background were investigated. The obtained results allow us to conclude that the main host lattice excitation relevant to both the luminescence processes mentioned above is a very mobile excitonic excitation including a photon phase and the self- trapped exciton in its composition. The photon phase, as we suppose, represents a free exciton luminescence at room temperature. In this phase, via multiple reabsorption in the low-ene…
FTICR analysis of the magnetic trapping mode of the electron beam ion trap
1996
Abstract An electron beam ion trap is used to produce and confine highly-charged atomic ions in an energetic electron beam (electron trapping mode). After switching off the electron beam the ions remain trapped due to the external magnetic and electric fields. We have investigated the properties of this magnetic trapping mode by use of Fourier transform ion cyclotron resonance mass spectrometry. We found that the number of highly charged ions and the relative species abundance is nearly the same just before and just after turning off the electron beam. The electron trapping mode thus represents an ideal method for filling the trap in situ without the losses associated with transferring the …
A Scanning Electron Microscope for Ultracold Atoms
2006
We propose a new technique for the detection of single atoms in ultracold quantum gases. The technique is based on scanning electron microscopy and employs the electron impact ionization of trapped atoms with a focussed electron probe. Subsequent detection of the resulting ions allows for the reconstruction of the atoms position. This technique is expected to achieve a much better spatial resolution compared to any optical detection method. In combination with the sensitivity to single atoms, it makes new in situ measurements of atomic correlations possible. The detection principle is also well suited for the addressing of individual sites in optical lattices.
Pulsed gas injection for X-ray spectroscopy of highly charged ions stored in the magnetic trapping mode of an electron beam ion trap
1998
Abstract Highly charged atoms produced in an electron beam ion trap were stored after the electron beam was turned off by operating the trap in the magnetic trapping mode. Such storage allowed monitoring charge exchange reactions between the stored ions and residual neutral gas present in the trap by X-ray detection. The charge exchange reactions were enhanced by the application of a pulse of neutral gas. The method was exemplified for the case of H-like uranium interacting with neutral neon, where the K-shell X-rays and the series limit for the electron capture of U91+ were observed.
EBIT trapping program
1993
The LLNL electron beam ion trap provides the world's only source of stationary highly charged ions up to bare U. This unique capability makes many new atomic and nuclear physics experiments possible.