Conditional Transition Systems with Upgrades

We introduce a variant of transition systems, where activation of transitions depends on conditions of the environment and upgrades during runtime potentially create additional transitions. Using a cornerstone result in lattice theory, we show that such transition systems can be modelled in two ways: as conditional transition systems (CTS) with a partial order on conditions, or as lattice transition systems (LaTS), where transitions are labelled with the elements from a distributive lattice. We define equivalent notions of bisimilarity for both variants and characterise them via a bisimulation game. We explain how conditional transition systems are related to featured transition systems for the modelling of software product lines. Furthermore, we show how to compute bisimilarity symbolically via BDDs by defining an operation on BDDs that approximates an element of a Boolean algebra into a lattice. We have implemented our procedure and provide runtime results

Electron gun for diffraction experiments off controlled molecules

A dc electron gun, generating picosecond pulses with up to $8\times10^{6}$ electrons per pulse, was developed. Its applicability for future time-resolved-diffraction experiments on state- and conformer-selected laser-aligned or oriented gaseous samples was characterized. The focusing electrodes were arranged in a velocity-map imaging spectrometer configuration. This allowed to directly measure the spatial and velocity distributions of the electron pulses emitted from the cathode. The coherence length and pulse duration of the electron beam were characterized by these measurements combined with electron trajectory simulations. Electron diffraction data off a thin aluminum foil illustrated the coherence and resolution of the electron-gun setup

Spatially-controlled complex molecules and their applications

The understanding of molecular structure and function is at the very heart of the chemical and molecular sciences. Experiments that allow for the creation of structurally pure samples and the investigation of their molecular dynamics and chemical function have developed tremendously over the last few decades, although "there's plenty of room at the bottom" for better control as well as further applications. Here, we describe the use of inhomogeneous electric fields for the manipulation of neutral molecules in the gas-phase, \ie, for the separation of complex molecules according to size, structural isomer, and quantum state. For these complex molecules, all quantum states are strong-field seeking, requiring dynamic fields for their confinement. Current applications of these controlled samples are summarised and interesting future applications discussed.Comment: Accepted by Int. Rev. Phys. Che

Ultrafast light-induced dynamics in solvated biomolecules: The indole chromophore with water

Interactions between proteins and their solvent environment can be studied in a bottom-up approach using hydrogen-bonded chromophore-solvent clusters. The ultrafast dynamics following UV-light-induced electronic excitation of the chromophores, potential radiation-damage, and their dependence on solvation are important open questions. The microsolvation effect is challenging to study due to the inherent mix of the produced gas-phase aggregates. We used the deflector to spatially separate different molecular species in combination with pump-probe velocity-map-imaging experiments. We demonstrated that this powerful experimental approach reveals intimate details of the UV-induced dynamics in the near-UV-absorbing prototypical biomolecular indole-water system. We determined the time-dependent appearance of the different reaction products and disentangled the occurring ultrafast processes. This novel approach ensures that the reactants are well-known and that detailed characteristics of the specific reaction products are accessible -- paving the way for the complete chemical-reactivity experiment

Concatenation and other Closure Properties of Recognizable Languages in Adhesive Categories

We consider recognizable languages of cospans in adhesive categories, ofwhich recognizable graph languages are a special case. We show that such languages are closed under concatenation, i.e. under cospan composition, by providing a con-crete construction that creates a concatenation automaton from two given automata.The construction is considerably more complex than the corresponding construction for finite automata. We conclude by showing negative closure properties for Kleene star and substitution

Strongly aligned and oriented molecular samples at a kHz repetition rate

We demonstrate strong adiabatic laser alignment and mixed-field orientation at kHz repetition rates. We observe degrees of alignment as large as cos\Theta=0.94 at 1 kHz operation for iodobenzene. The experimental setup consist of a kHz laser system simultaneously producing pulses of 30 fs (1.3 mJ) and 450 ps (9 mJ). A cold 1 K state-selected molecular beam is produced at the same rate by appropriate operation of an Even-Lavie valve. Quantum state selection has been obtained using an electrostatic deflector. A camera and data acquisition system records and analyzes the images on a single-shot basis. The system is capable of producing, controlling (translation and rotation) and analyzing cold molecular beams at kHz repetition rates and is, therefore, ideally suited for the recording of ultrafast dynamics in so-called "molecular movies".Comment: 6 pages, 4 figures, in press in Mol. Phys., accepted in February 2013, in final production (galley proofs done) since March 8, 2013, v3 only adds publication dat