Spatially separated polar samples of the cis and trans conformers of 3-fluorophenol

We demonstrate the spatial separation of the cis- and trans-conformers of 3-fluorophenol in the gas phase based on their distinct electric dipole moments. For both conformers we create very polar samples of their lowest-energy rotational quantum states. A >95 % pure beam of trans-3-fluorophenol and a >90 % pure beam of the lowest-energy rotational states of the less polar cis-3-fluorophenol were obtained for helium and neon supersonic expansions, respectively. This is the first demonstration of the spatial separation of the lowest-energy rotational states of the least polar conformer, which is necessary for strong alignment and orientation of all individual conformers.Comment: 5 pages, 5 figure

Long-term trapping of Stark-decelerated molecules

Trapped cold molecules represent attractive systems for precision-spectroscopic studies and for investigations of cold collisions and chemical reactions. However, achieving their confinement for sufficiently long timescales remains a challenge. Here, we report the long-term trapping of Stark-decelerated OH radicals in their X (2)Pi(3/2) (nu = 0, J = 3/2, M-J = 3/2, f) state in a permanent magnetic trap. The trap environment is cryogenically cooled to a temperature of 17 K to suppress black-body-radiation-induced pumping of the molecules out of trappable quantum states and collisions with residual background gas molecules which usually limit the trap lifetime. The cold molecules are thus confined on timescales approaching minutes, an improvement of up to two orders of magnitude compared with room temperature experiments, at translational temperatures of similar to 25 mK. The present results pave the way for new experiments using trapped cold molecules in precision spectroscopy, in studies of slow chemical processes at low energies and in the quantum technologies

Knife edge skimming for improved separation of molecular species by the deflector

A knife edge for shaping a molecular beam is described to improve the spatial separation of the species in a molecular beam by the electrostatic deflector. The spatial separation of different molecular species from each other as well as from atomic seed gas is improved. The column density of the selected molecular-beam part in the interaction zone, which corresponds to higher signal rates, was enhanced by a factor of 1.5, limited by the virtual source size of the molecular beam.Comment: 3 pages, 2 figure

Spatial separation of pyrrole and pyrrole-water clusters

We demonstrate the spatial separation of pyrrole and pyrrole(H$_2$O) clusters from the other atomic and molecular species in a supersonically-expanded beam of pyrrole and traces of water seeded in high-pressure helium gas. The experimental results are quantitatively supported by simulations. The obtained pyrrole(H$_2$O) cluster beam has a purity of ~100 %. The extracted rotational temperature of pyrrole and pyrrole(H$_2$O) from the original supersonic expansion is $T_\text{rot}=0.8\pm0.2$ K, whereas the temperature of the deflected, pure-pyrrole(H$_2$O) part of the molecular beam corresponds to $T_\text{rot}\approx0.4$ K

Photophysics of indole upon x-ray absorption

A photofragmentation study of gas-phase indole (C$_8$H$_7$N) upon single-photon ionization at a photon energy of 420 eV is presented. Indole was primarily inner-shell ionized at its nitrogen and carbon $1s$ orbitals. Electrons and ions were measured in coincidence by means of velocity map imaging. The angular relationship between ionic fragments is discussed along with the possibility to use the angle-resolved coincidence detection to perform experiments on molecules that are strongly oriented in their recoil-frame. The coincident measurement of electrons and ions revealed fragmentation-pathway-dependent electron spectra, linking the structural fragmentation dynamics to different electronic excitations. Evidence for photoelectron-impact self-ionization was observed.Comment: 11 pages, 6 figure

Der Einfluss von Normen in Verlustexperimenten

Wir haben experimentell untersucht, welche Wirkung Normen in Verlustsituationen haben. Hierfür haben wir negative Diktator- und Ultimatumspiele durchgeführt und dabei in einem Treatment „Referenzwert“ den Fokus auf die deskriptive Norm gesetzt, welches Verhalten in der gegebenen Situation typisch ist. In einem weiteren Treatment „Rationaler Spieler“ haben wir die spieltheoretische Lösung der beiden Spiele angegeben um damit den Fokus vom üblichen fokalen Punkt der Gleichaufteilung abzulenken.:1. Einleitung 2. Theorie und Hypothesen 2.1 Wirkung einer Gleichaufteilungsnorm in Aufteilungs- und Verhandlungsproblemen 2.2 Wirkung deskriptiver Normen 2.3 Robustheit der Gleichverteilungsnorm 3. Methode und Treatments 4. Auswertungen 4.1 Ergebnisse zu den vermuteten Haupteffekten 4.2 Explorative Effekte zu Interaktion aus Studiengang und Treatment 5. Zusammenfassung und Interpretation der Ergebniss

Norm focusing and losses—Evidence of ultimatum game experiments

IntroductionHuman decision-making pertaining to gains compared to those pertaining losses is shown to be quite different. However, mixed evidence is provided regarding the effect on the decision-makers' prosocial behaviors; that is, losses are shown to either increase or decrease prosocial behaviors. In this context, the effect of social norms on observed behavior can play a crucial role.MethodsTo examine this aspect in more detail, we conducted incentivized ultimatum game experiments and analyzed data from three treatments, the control treatments (without specific norm focus), and two different norm-focus treatments (“average behavior” treatment and “self-interested behavior” treatment). In total, 550 participants took part in our experiment. Basically, we found no significant difference between the division of gains and losses in the “control” and “self-interested behavior” treatments.Results and discussionHowever, we found such a difference in the “average behavior” treatment. In addition, we found that inducing a norm focus leads to less variance in proposers' behavior and a greater concentration of their demands around the induced norm in the “average behavior” treatment. In contrast, we found a higher variance in proposers' behavior in the “self-interested behavior” treatment. In terms of responders' behaviors, we observed a tendency toward a higher frequency of responders' rejections in the loss domain compared to the gains domain

High-repetition-rate and high-photon-flux 70 eV high-harmonic source for coincidence ion imaging of gas-phase molecules

Unraveling and controlling chemical dynamics requires techniques to image structural changes of molecules with femtosecond temporal and picometer spatial resolution. Ultrashort-pulse x-ray free-electron lasers have significantly advanced the field by enabling advanced pump-probe schemes. There is an increasing interest in using table-top photon sources enabled by high-harmonic generation of ultrashort-pulse lasers for such studies. We present a novel high-harmonic source driven by a 100 kHz fiber laser system, which delivers 10$^{11}$ photons/s in a single 1.3 eV bandwidth harmonic at 68.6 eV. The combination of record-high photon flux and high repetition rate paves the way for time-resolved studies of the dissociation dynamics of inner-shell ionized molecules in a coincidence detection scheme. First coincidence measurements on CH$_3$I are shown and it is outlined how the anticipated advancement of fiber laser technology and improved sample delivery will, in the next step, allow pump-probe studies of ultrafast molecular dynamics with table-top XUV-photon sources. These table-top sources can provide significantly higher repetition rates than the currently operating free-electron lasers and they offer very high temporal resolution due to the intrinsically small timing jitter between pump and probe pulses

Strongly aligned gas-phase molecules at Free-Electron Lasers

We demonstrate a novel experimental implementation to strongly align molecules at full repetition rates of free-electron lasers. We utilized the available in-house laser system at the coherent x-ray imaging beamline at the Linac Coherent Light Source. Chirped laser pulses, i. e., the direct output from the regenerative amplifier of the Ti:Sa chirped pulse amplification laser system, were used to strongly align 2,5-diiodothiophene molecules in a molecular beam. The alignment laser pulses had pulse energies of a few mJ and a pulse duration of 94 ps. A degree of alignment of \left = 0.85 was measured, limited by the intrinsic temperature of the molecular beam rather than by the available laser system. With the general availability of synchronized chirped-pulse-amplified near-infrared laser systems at short-wavelength laser facilities, our approach allows for the universal preparation of molecules tightly fixed in space for experiments with x-ray pulses.Comment: 10 pages, 5 figure