A5046866379- Advanced Chemical Physics Studies
- Mass Spectrometry Techniques and Applications
- Spectroscopy and Laser Applications
- Spectroscopy and Quantum Chemical Studies
- Laser-Matter Interactions and Applications
- Atmospheric Ozone and Climate
- Ion-surface interactions and analysis
- Astrophysics and Star Formation Studies
- Molecular Junctions and Nanostructures
- Radiation Therapy and Dosimetry
- Molecular spectroscopy and chirality
- Radiation Effects in Electronics
- Nuclear Physics and Applications
- Molecular Spectroscopy and Structure
- Fluorine in Organic Chemistry
Universität Innsbruck
2012-2017
University of Freiburg
2009-2011
The competition between bimolecular nucleophilic substitution and base-induced elimination is of fundamental importance for the synthesis pure samples in organic chemistry. Many factors that influence this have been identified over years, but underlying atomistic dynamics remained difficult to observe. We present product velocity distributions a series reactive collisions type X- + RY with X Y denoting halogen atoms fluorine, chlorine iodine. By increasing size residue R from methyl...
We present a study of the different product channels in reactions OH− and OH−(H2O) with methyl iodide over range collision energies. Direct dynamics classical trajectory simulations are employed to obtain an atomistic comparison experimental results. For experiments we have combined crossed beam ion imaging setup multipole rf trap. The trap allows us prepare molecular cluster ions controlled internal temperature thus provides well-defined initial conditions for reaction at low energy....
Nucleophilic substitution (SN2) and base-induced elimination (E2), two indispensable reactions in organic synthesis, are commonly assumed to proceed under stereospecific conditions. Understanding the way which reactants pre-orient these reactions, that is its stereodynamics, essential order achieve a detailed atomistic picture control over such processes. Using crossed beam velocity map imaging, we study effect of steric hindrance Cl- CN- with increasingly methylated alkyl iodides by...
Electrostatic ion imaging with the velocity map mode is a widely used method in atomic and molecular physics physical chemistry. In contrast, spatial (SMI) has received very little attention, despite fact that it been proposed earlier [A. T. J. B. Eppink D. H. Parker, Rev. Sci. Instrum. 68, 3477 (1997)]. Here, we present detailed parametric characterization of SMI both by simulation experiment. One-, two- three-dimensional modes are described. The influence different parameters on process...
The charge transfer reaction Ar+ + N2 --> Ar N2+ has been investigated in a crossed beam experiment combination with three-dimensional velocity map imaging. Angular differential state-to-state cross sections were determined as function of the collision energy. We found that scattering into first excited vibrational level dominates expected, but only for forward direction. Higher excitations up to v'=6 have observed larger angles. For decreasing energy, higher angles becomes increasingly...
We report on the reaction dynamics of monosolvated SN2 cold OH(-)(H2O) with CH3I that have been studied using crossed beam ion imaging. Two channels are possible for this reaction: Formation unsolvated I(-) and solvated I(-)(H2O) products. find a strong preference formation products respect to energetically favored toward I(-)(H2O). Angle differential cross section measurements reveal similar velocity angular distributions all parts furthermore contribution these two total product flux can...
Ion–molecule reactions of the type X– + CH3Y are commonly assumed to produce Y– through bimolecular nucleophilic substitution (SN2). Beyond this reaction, additional reaction products have been observed throughout last decades and ascribed different entrance channel geometries differing from collinear approach. We performed a crossed beam velocity map imaging experiment on F– CH3I at relative collision energies between 0.4 2.9 eV. find three channels competing with high energies....
The nucleophilic substitution reaction CN− + CH3I allows for two possible reactive approaches of the reactant ion onto methyl halide, which lead to different product isomers. Stationary point calculations predict a similar shape potential and dominant collinear approach both attacks. In addition, an H-bonded pre-reaction complex is identified as intermediate structure. Submerged energy barriers hint at statistical formation process CNCH3 NCCH3 isomers experimental collision energies....
Kinematically complete studies of molecular reactions offer an unprecedented level insight into the dynamics and different mechanisms by which chemical occur. We have developed a scheme to study ion-molecule velocity map imaging at very low collision energies. Results for elementary nucleophilic substitution (SN2) reaction Cl- + CH3I → ClCH3 I- are presented compared high-level direct trajectory calculations. Furthermore, improved design crossed-beam spectrometer with full three-dimensional...
The proton transfer reaction H3+ + CO is one of the cornerstone chemical processes in interstellar medium. Here, dynamics this have been investigated using crossed beam velocity map imaging. Formyl product cations are found to be predominantly scattered into forward direction irrespective collision energy. In process, a high amount energy transferred internal excitation. By fitting sum two distribution functions measured distributions, isomer ratio extracted. A small HOC+ fraction obtained...
The rotationally inelastic scattering of methyl radical with Ar and N2 is examined at collision energies 330 ± 25 cm(-1) 425 50 cm(-1), respectively. Differential cross sections (DCSs) were measured for different final n' rotational levels (up to = 5) the radicals, averaged over k' sub-levels, using a crossed molecular beam machine velocity map imaging. For as partner, we present newly constructed ab initio potential energy surface quantum mechanical calculations state-resolved DCSs. These...
The proton transfer reaction HOCO++CO → HCO+/HOC+ has been studied using crossed-beam velocity map imaging. Angular and energy differential cross sections were obtained for collision energies from 0.3 to 2.3 eV. Scattering in forward direction together with a prominent scattering angle-dependent internal excitation is found at all energies. exothermic HCO+ product appears be very dominant even above the threshold formation of metastable HOC+ ion. To determine contribution different angular...
Adiabatic alignment of CH3I, induced by the anisotropic interaction this symmetric top molecule with intense field a nonresonant infrared laser pulse, has been studied using velocity map imaging. We are photodissociation imaging pulsed nanosecond lasers to probe distribution molecular axis in laboratory space. In contrast commonly used probing femtosecond pulses, technique directly yields degree over an extended space–time volume. This will be relevant for future reactive scattering...