Oldrich Novotny
Max Planck Society
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Featured researches published by Oldrich Novotny.
Science | 2013
Philipp Herwig; Kerstin Zawatzky; M. Grieser; O. Heber; Brandon Jordon-Thaden; Claude Krantz; Oldrich Novotny; R. Repnow; Volker Schurig; D. Schwalm; Zeev Vager; A. Wolf; Oliver Trapp; Holger Kreckel
Foil-Forged Images X-ray diffraction is widely used to determine molecular geometries and can often distinguish mirror image isomers (enantiomers), which generally requires well-ordered crystals. Herwig et al. (p. 1084) report an imaging technique to characterize enantiomers in the gas phase. A succession of ionization events were induced by passage through a carbon foil that culminated in a Coulomb explosion of mutually repelling nuclei. The trajectories of these nuclei precisely reflected the original molecular structure. Ultrafast electron stripping by a carbon foil enables precise elucidation of molecular geometries as the nuclei fly apart. In chemistry and biology, chirality, or handedness, refers to molecules that exist in two spatial configurations that are incongruent mirror images of one another. Almost all biologically active molecules are chiral, and the correct determination of their absolute configuration is essential for the understanding and the development of processes involving chiral molecules. Anomalous x-ray diffraction and vibrational optical activity measurements are broadly used to determine absolute configurations of solid or liquid samples. Determining absolute configurations of chiral molecules in the gas phase is still a formidable challenge. Here we demonstrate the determination of the absolute configuration of isotopically labeled (R,R)-2,3-dideuterooxirane by foil-induced Coulomb explosion imaging of individual molecules. Our technique provides unambiguous and direct access to the absolute configuration of small gas-phase species, including ions and molecular fragments.
Journal of Physical Chemistry A | 2010
Oldrich Novotny; Henrik Buhr; Julia Stützel; Mario B. Mendes; Max H. Berg; Dennis Bing; M. Froese; M. Grieser; O. Heber; Brandon Jordon-Thaden; Claude Krantz; M. Lange; M. Lestinsky; Steffen Novotny; Sebastian Menk; Dmitry A. Orlov; Annemieke Petrignani; M. L. Rappaport; Andrey Shornikov; D. Schwalm; A. Wolf
We report on our recent studies of dissociative recombination (DR) employing two different fragment imaging detection techniques at the TSR storage ring in Heidelberg, Germany. Principles of an upgraded 3D optical system and the new energy-sensitive multistrip detector (EMU) are explained together with possible applications in reaction dynamics studies. With the EMU imaging detector we succeeded to observe the branching ratios after DR of deuterated hydronium ions D(3)O(+) at energies of 0-0.5 and 4-21 eV. The branching ratios are almost constant at low energies while above 6 eV both oxygen-producing channels O + D + D + D and O + D(2) + D strongly increase and dominate by about 85% at 11 eV. To demonstrate further capabilities of our fragment imaging detectors, we also summarize some of our additional recent studies on DR of molecular ions important for astrophysics as well as for fundamental unimolecular dynamics.
XXV International Conference on Photonic, Electronic and Atomic Collisions | 2007
Holger Kreckel; Annemieke Petrignani; Max H. Berg; Dennis Bing; S. Reinhardt; S. Altevogt; Hendrik Buhr; M. Froese; Jens Hoffmann; Brandon Jordon-Thaden; Claude Krantz; M. Lestinsky; Mario B. Mendes; Oldrich Novotny; Steffen Novotny; H. B. Pedersen; D. A. Orlov; J. Mikosch; Radek Plašil; J. Glosik; D. Schwalm; A. Wolf
Electron recombination of H3+ has found a lot of attention due to its outstanding relevance for the chemistry of the interstellar medium (ISM) and its role as a benchmark for the treatment of dissociative recombination (DR) of polyatomic ions. We report DR measurements performed at the TSR storage ring utilizing a cryogenic ion trap injector. Furthermore, a chemical probing spectroscopy technique is described that allows for a very sensitive monitoring of the populated states inside the ion injector. Since H3+ exists in two different nuclear spin modifications, a controlled manipulation of the ortho/para fraction is needed in order to perform state-selective measurements.
Physical Review A | 2012
S. Schippers; D. Bernhardt; A. Müller; M. Lestinsky; Michael Hahn; Oldrich Novotny; Daniel Wolf Savin; M. Grieser; Claude Krantz; R. Repnow; A. Wolf
The hyperfine induced 2s 2p 3P0 -> 2s2 1S0 transition rate in Be-like sulfur was measured by monitoring the decay of isotopically pure beams of 32-S12+ and 33-S12+ ions in a heavy-ion storage ring. Within the 4% experimental uncertainty the experimental value of 0.096(4)/s agrees with the most recent theoretical results of Cheng et al. [Phys. Rev. A 77, 052504 (2008)] and Andersson et al. [Phys. Rev. A 79, 032501 (2009)]. Repeated experiments with different magnetic fields in the storage-ring bending magnets demonstrate that artificial quenching of the 2s 2p 3P0 state by these magnetic fields is negligible.
Journal of Physical Chemistry A | 2010
Annemieke Petrignani; Dennis Bing; Oldrich Novotny; Max H. Berg; Henrik Buhr; M. Grieser; Brandon Jordon-Thaden; Claude Krantz; Mario B. Mendes; Sebastian Menk; Steffen Novotny; D. A. Orlov; R. Repnow; J Stützel; Xavier Urbain; A. Wolf
Ultraviolet and visible photodissociation of a vibrationally excited H(3)(+) ion beam, as produced by standard ion sources, was successfully implemented in an ion storage ring with the aim of investigating the decay of the excited molecular levels. A collinear beams configuration was used to measure the photodissociation of H(3)(+) into H(2)(+) + H fragments by transitions into the first excited singlet state with 266 and 532 nm laser beams. A clear signal could be observed up to 5 ms of storage, indicating that enough highly excited rovibrational states survive on the millisecond time scale of the experiment. The decay into H(2)(+) + H shows an effective time constant between about 1 and 1.5 ms. The initial photodissociating states are estimated to lie roughly 1 eV below the dissociation limit of 4.4 eV. The expected low population of these levels gives rise to an effective cross section of several 10(-20) cm(2) for ultraviolet and some 10(-21) cm(2) for visible light. For using multistep resonant dissociation schemes to monitor rotational populations of cold H(3)(+) in low-density environments, these measurements open promising perspectives.
The Astrophysical Journal | 2015
Michael Hahn; Arno Becker; D. Bernhardt; M. Grieser; Claude Krantz; M. Lestinsky; A. Müller; Oldrich Novotny; R. Repnow; S. Schippers; K. Spruck; A. Wolf; Daniel Wolf Savin
We report electron impact ionization cross section measurements for electron impact single ionization of Fe 12+ forming Fe 13+ and electron impact double ionization of Fe 12+ forming Fe 14+ . These are the first electron impact ionization data for any Si-like ion uncontaminated by an unknown metastable fraction. Recent distorted wave calculations agree with our single ionization results to within ∼15%. Double ionization is dominated by inner shell ionization of a 2l electron resulting in autoionization of a second electron as the inner shell hole is filled.
arXiv: Atomic Physics | 2009
Steffen Novotny; H. Rubinstein; Henrik Buhr; Oldrich Novotny; Jens Hoffmann; Mario B. Mendes; D. A. Orlov; Max H. Berg; M. Froese; A. S. Jaroshevich; Brandon Jordon-Thaden; M. Grieser; Claude Krantz; M. Lange; M. Lestinsky; Annemieke Petrignani; I. F. Schneider; D. Shafir; F. O. Waffeu Tamo; D. Schwalm; A. Wolf
On a dense energy grid reaching up to 75 meV electron collision energy the fragmentation angle and the kinetic energy release of neutral dissociative recombination fragments have been studied in a twin merged beam experiment. The anisotropy and the extracted rotational state contributions were found to sensitively depend on energy. Both show pronounced variations on a likewise narrow energy scale as the rotationally averaged rate coefficient. For the first time angular dependences described by Legendre polynomials higher than 2nd order could be deduced. Moreover, a slight anisotropy at zero collision energy was observed which is caused by the flattened velocity distribution of the electron beam.
The Astrophysical Journal | 2014
Michael Hahn; N. R. Badnell; M. Grieser; Claude Krantz; M. Lestinsky; A. Müller; Oldrich Novotny; R. Repnow; S. Schippers; A. Wolf; Daniel Wolf Savin
We have measured dielectronic recombination (DR) for Fe12 + forming Fe11 + using the heavy ion storage ring TSR located at the Max Planck Institute for Nuclear Physics in Heidelberg, Germany. Using our results, we have calculated a plasma rate coefficient from these data that can be used for modeling astrophysical and laboratory plasmas. For the low temperatures characteristic of photoionized plasmas, the experimentally derived rate coefficient is orders of magnitude larger than the previously recommended atomic data. The existing atomic data were also about 40% smaller than our measurements at temperatures relevant for collisionally ionized plasmas. Recent state-of-the-art theory has difficulty reproducing the detailed energy dependence of the DR spectrum. However, for the Maxwellian plasma rate coefficient, recent theoretical results agree with our measurements to within about 30% for both photoionized and collisionally ionized plasmas.
Journal of Physics: Conference Series | 2011
D. Schwalm; D. Shafir; Oldrich Novotny; Henrik Buhr; S. Altevogt; A. Faure; M. Grieser; Alex G. Harvey; O. Heber; Jens Hoffmann; Holger Kreckel; L. Lammich; O. Motapon; I. Nevo; H. B. Pedersen; H. Rubinstein; I. F. Schneider; Jonathan Tennyson; F O Waffeu Tamo; A. Wolf
Rotational cooling of HD+ by superelastic collisions (SEC) with electrons was observed at the Heidelberg test storage ring by merging a beam of rotationally hot HD+ ions with an electron beam at zero relative energy. Neutral fragments resulting from DR events were recorded at different electron densities using a high resolution imaging detector and a large-area, energy sensitive detector. The data allowed to deduce the time dependence of the population of three groups of rotational angular momentum states J built on the vibrational ground state of the ion together with the corresponding DR rate coefficients. The latter are found to be (statistical uncertainties only) α0,1,2 = 3.8(1), α3,4 = 4.0(2), and α5,6,7 = 9.0(1.3) in units of 10−8 cm3/s, in reasonable agreement with the average values derived within the MQDT approach. The time evolution of the population curves clearly reveals that rotational cooling by SEC takes place, which can be well described by using theoretical SEC rate coefficients obtained by combining the molecular R-matrix approach with the adiabatic nuclear rotation approximation. We verify the ΔJ = −2 coefficients, which are predicted to be dominant as opposed to the ΔJ = −1 coefficients and to amount to (1 − 2) 10−6 cm3/s, to within 30%.
Archive | 2010
Daniel Wolf Savin; Michael Hahn; M. Lestinsky; Oldrich Novotny; D. Bernhardt; A Müller; S. Schippers; Claude Krantz; M. Grieser; R. Repnow; A. Wolf
Knowledge of the charge state distribution (CSD) of astrophysical plasmas is important for the interpretation of spectroscopic data. To accurately calculate CSDs, reliable rate coefficients are needed for dielectronic recombination (DR), which is the dominant electron-ion recombination mechanism for most ions, and for electron impact ionization (EII). We are carrying out DR and EII measurements of astrophysically important ions using the TSR storage ring at the Max-Plank-Institute for Nuclear Physics in Heidelberg, Germany. Storage ring measurements are largely free of the metastable contamination found in other experimental geometries, resulting in more unambiguous DR and EII reaction rate measurements. The measured data can be used in plasma modelling as well as for benchmarking theoretical atomic calculations.