Surface plasma resonance in small rare gas clusters by mixing IR and VUV laser pulses

The ionization dynamics of a Xenon cluster with 40 atoms is analyzed under a pum p probe scenario of laser pulses where an infrared laser pulse of 50 fs length follows with a well defined time delay a VUV pulse of the same length and peak intensity. The mechanism of resonant energy absorption due to the coinc idence of the IR laser frequency with the frequency of collective motion of quasi free electrons in the cluster is mapped out by varying the time delay between the pulses

Ionization and charge migration through strong internal fields in clusters exposed to intense X-ray pulses

A general scenario for electronic charge migration in finite samples illuminated by an intense laser pulse is given. Microscopic calculations for neon clusters under strong short pulses as produced by X-ray free-electron laser sources confirm this scenario and point to the prominent role of field ionization by strong internal fields. The latter leads to the fast formation of a core-shell system with an almost static core of screened ions while the outer shell explodes. Substituting the shell ions with a different material such as helium as a sacrificial layer leads to a substantial improvement of the diffraction image for the embedded cluster thus reducing the consequences of radiation damage for coherent diffractive imaging.Comment: 5 pages, 4 figure

Dynamics of photo-activated Coulomb complexes

Intense light with frequencies above typical atomic or molecular ionization potentials as provided by free-electron lasers couples many photons into extended targets such as clusters and biomolecules. This implies, in contrast to traditional multi-photon ionization, multiple single-photon absorption. Thereby, many electrons are removed from their bound states and either released or trapped if the target charge has become sufficiently large. We develop a simple model for this photo activation to study electron migration and interaction. It satisfies scaling relations which help to relate quite different scenarios. To understand this type of multi-electron dynamics on very short time scales is vital for assessing the radiation damage inflicted by that type of radiation and to pave the way for coherent diffraction imaging of single molecules.Comment: 14 pages, 6 figures, 1 tabl

The fatal outcome of an individual with anorexia nervosa and Sheehan's syndrome as a result of acute enterocolitis: A case report

Objectives: To illustrate the close association between a disturbed psychosocial up-bringing, frequent physical illness, and medical interventions. Method: We report a case of a 44-year-old woman with anorexia nervosa (AN) and Sheehan's syndrome who died as a result of a toxic cardiac arrest. Results: The patient presented with a BMI of 13.6 kg/m2. She refused any intensive-care treatment and died from toxic cardiac arrest. Postmortem examination revealed an acute gastroenterocolitis. Discussion: The history of this patient illustrates how psychological deprivation led to eating disturbances, early pregnancy, and the life-threatening delivery of twins. This resulted in a diagnosis of Sheehan's syndrome, hepatitis C, and a ventricular ulcer. A psychosocial event triggered a late exacerbation of her AN. A helpful alliance between patient and staff did not occur as she rejected it

Electron release of rare gas atom clusters under an intense laser pulse

Calculating the energy absorption of atomic clusters as a function of the laser pulse length $T$ we find a maximum for a critical $T^*$. We show that $T^*$ can be linked to an optimal cluster radius $R^*$. The existence of this radius can be attributed to the enhanced ionization mechanism originally discovered for diatomic molecules. Our findings indicate that enhanced ionization should be operative for a wide class of rare gas clusters. From a simple Coulomb explosion ansatz, we derive an analytical expression relating the maximum energy release to a suitably scaled expansion time which can be expressed with the pulse length $T^*$.Comment: 4 pages, 5 figure