Showing papers by "Till Jahnke published in 2004"
TL;DR: In this paper, an experimental observation of ICD in $2s$ ionized neon dimers is reported, which is unambiguously identified by detecting the energy of two ${\mathrm{N}mathm{e}^{1+}$ fragments and the ICD electron in coincidence.
Abstract: Recently Cederbaum et al. [Phys. Rev. Lett. 79, 4778 (1997)] predicted a new decay channel of excited atoms and molecules termed interatomic Coulombic decay (ICD). In ICD the deexcitation energy is transferred via virtual photon exchange to a neighboring atom, which releases it by electron emission. We report on an experimental observation of ICD in $2s$ ionized neon dimers. The process is unambiguously identified by detecting the energy of two ${\mathrm{N}\mathrm{e}}^{1+}$ fragments and the ICD electron in coincidence, yielding a clean, background free experimental spectral distribution of the ICD electrons.
239 citations
TL;DR: In this paper, the authors introduce the method of measuring electron and ion momentum distributions from fixed-in-space molecules using modified versions of the COLTRIMS technique, followed by a detailed discussion of the design of the electron and the ion detection part of the spectrometer.
92 citations
TL;DR: Diffraction of a low energy carbon-K-photoelectron wave that is created inside a CO molecule by absorption of a circularly polarized photon is investigated and shows significant variation for the different vibrational states.
Abstract: Diffraction of a low energy ($l4\text{ }\text{ }\mathrm{e}\mathrm{V}$) carbon-$K$-photoelectron wave that is created inside a CO molecule by absorption of a circularly polarized photon is investigated. The measurements resolve the vibrational states of the $K$-shell ionized $\mathrm{C}{\mathrm{O}}^{\mathrm{+}}$ molecule and display the photoelectron diffraction patterns in the molecular frame. These show significant variation for the different vibrational states. This effect is stronger than predicted by state-of-the-art theory. As this study is performed close to C-$K$-threshold and, therefore, far below the molecule's $\ensuremath{\sigma}$-shape resonance, this surprisingly strong effect is not related to that resonance phenomenon.
48 citations
TL;DR: In this article, the authors describe the mechanisms by which the nonresonant interaction of photons with atoms can lead to direct emission of two electrons from an atom and discuss three different light-matter interactions: absorption of one (high energy) photon, Compton scattering of one photon (in both cases utilizing synchrotron radiation) and multiphoton processes in strong femtosecond laser fields.
26 citations
TL;DR: In this article, a fractional charge of the ion was fitted from the condition to get an agreement with the experimental position of the σ ∗ shape resonance for the K-shell cross section.
Abstract: Partial photoionization cross sections and the angular asymmetry parameter β for the C K-shell of the CO molecule have been calculated in the relaxed core Hartree–Fock approximation. In contrast with all previous calculations, we introduced the relaxed core potential with a fractional charge of the ion which was fitted from the condition to get an agreement with the experimental position of the σ ∗ shape resonance for the K-shell cross section. We found the optimal value of the fractional charge to be 0.5. After performing calculations within the Born–Oppenheimer approximation for several fixed internuclear distances R, we averaged the R-dependent dipole amplitudes over R with the vibrational wavefunctions of the initial and final states. Transitions from the ground vibrational level to several vibrationally excited states of the residual molecular ion have been studied within this approximation. A good agreement was found with the recently published vibrationally resolved experimental data.
25 citations