RESUMEN
We present experimental data on strong-field ionization of atomic hydrogen by few-cycle laser pulses. We obtain quantitative agreement at the 10% level between the data and an ab initio simulation over a wide range of laser intensities and electron energies.
RESUMEN
In electron-transfer processes, spin effects normally are seen either in magnetic materials or in systems containing heavy atoms that facilitate spin-orbit coupling. We report spin-selective transmission of electrons through self-assembled monolayers of double-stranded DNA on gold. By directly measuring the spin of the transmitted electrons with a Mott polarimeter, we found spin polarizations exceeding 60% at room temperature. The spin-polarized photoelectrons were observed even when the photoelectrons were generated with unpolarized light. The observed spin selectivity at room temperature was extremely high as compared with other known spin filters. The spin filtration efficiency depended on the length of the DNA in the monolayer and its organization.
Asunto(s)
ADN , Electrones , Oro , ADN/química , Rayos Láser , Conformación de Ácido Nucleico , Fenómenos Físicos , Estereoisomerismo , Temperatura , Rayos UltravioletaRESUMEN
Triple differential cross sections for the electron-impact ionization of the outer valence orbital of tetrahydrofuran have been measured using the (e, 2e) technique. The measurements have been performed with coplanar asymmetric kinematics, at an incident electron energy of 250 eV and at an ejected electron energy of 10 eV, over a range of momentum transfers. The experimental results are compared with theoretical calculations carried out using the molecular three-body distorted wave model. The results obtained are important for gaining an understanding of electron driven processes at a molecular level and for modeling energy deposition in living tissue.
Asunto(s)
ADN/química , Electrones , Transferencia de Energía , Furanos/química , Modelos Biológicos , Fenómenos Biomecánicos , Transferencia Lineal de EnergíaRESUMEN
The design of a compact multiangle electron analyzer array for simultaneous detection of scattered and ejected electrons at nine different angles is described. It consists of eight slim "simulated" cylindrical mirror analyzers (CMAs) providing electron detection for scattering/ejected angles of 14 degrees apart from each other. A ninth analyzer is arranged to a scattering angle on the opposite side. A single analyzer has cylindrical symmetry equipotential lines in the region of the beam trajectories, whereas its electrodes are noncylindrical, except for the inner cylinder. The new spectrometer is easy to build because only a few electrodes of simple shape are needed for each of the analyzers. The electron optical properties of the new device are very close to those of a true CMA. Its geometric width, however, is only less than one-fifth of that of a conventional CMA, which allows one to arrange several analyzers close to each other. Example results with the new device are presented.