3,294 research outputs found
Ion impact induced Interatomic Coulombic Decay in neon and argon dimers
We investigate the contribution of Interatomic Coulombic Decay induced by ion
impact in neon and argon dimers (Ne and Ar) to the production of low
energy electrons. Our experiments cover a broad range of perturbation strengths
and reaction channels. We use 11.37 MeV/u S, 0.125 MeV/u He,
0.1625 MeV/u He and 0.150 MeV/u He as projectiles and study
ionization, single and double electron transfer to the projectile as well as
projectile electron loss processes. The application of a COLTRIMS reaction
microscope enables us to retrieve the three-dimensional momentum vectors of the
ion pairs of the fragmenting dimer into Ne/Ne and
Ar/Ar (q = 1, 2, 3) in coincidence with at least one emitted
electron
Correlated Photon-Pair Emission from a Charged Single Quantum Dot
The optical creation and recombination of charged biexciton and trion
complexes in an (In,Ga)As/GaAs quantum dot is investigated by
micro-photoluminescence spectroscopy. Photon cross-correlation measurements
demonstrate the temporally correlated decay of charged biexciton and trion
states. Our calculations provide strong evidence for radiative decay from the
excited trion state which allows for a deeper insight into the spin
configurations and their dynamics in these systems.Comment: 5 pages, 3 figures, submitted for publicatio
Single photon double ionization of the helium dimer
We show that a single photon can ionize the two helium atoms of the helium
dimer in a distance up to 10 {\deg}A. The energy sharing among the electrons,
the angular distributions of the ions and electrons as well as comparison with
electron impact data for helium atoms suggest a knock-off type double
ionization process. The Coulomb explosion imaging of He_2 provides a direct
view of the nuclear wave function of this by far most extended and most diffuse
of all naturally existing molecules.Comment: 10 pages, 5 figure
Interatomic Coulombic Decay following Photoionization of the Helium Dimer: Observation of Vibrational Structure
Using synchrotron radiation we simultaneously ionize and excite one helium
atom of a helium dimer (He_2) in a shakeup process. The populated states of the
dimer ion (i.e. He^[*+](n = 2; 3)-He) are found to deexcite via interatomic
coulombic decay. This leads to the emission of a second electron from the
neutral site and a subsequent coulomb explosion. In this letter we present a
measurement of the momenta of fragments that are created during this reaction.
The electron energy distribution and the kinetic energy release of the two He^+
ions show pronounced oscillations which we attribute to the structure of the
vibrational wave function of the dimer ion.Comment: 8 pages, 5 figure
Influence of symmetry and Coulomb-correlation effects on the optical properties of nitride quantum dots
The electronic and optical properties of self-assembled InN/GaN quantum dots
(QDs) are investigated by means of a tight-binding model combined with
configuration interaction calculations. Tight-binding single particle wave
functions are used as a basis for computing Coulomb and dipole matrix elements.
Within this framework, we analyze multi-exciton emission spectra for two
different sizes of a lens-shaped InN/GaN QD with wurtzite crystal structure.
The impact of the symmetry of the involved electron and hole one-particle
states on the optical spectra is discussed in detail. Furthermore we show how
the characteristic features of the spectra can be interpreted using a
simplified Hamiltonian which provides analytical results for the interacting
multi-exciton complexes. We predict a vanishing exciton and biexciton ground
state emission for small lens-shaped InN/GaN QDs. For larger systems we report
a bright ground state emission but with drastically reduced oscillator
strengths caused by the quantum confined Stark effect.Comment: 15 pages, 17 figure
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