A5074897215- Atomic and Molecular Physics
- Advanced Chemical Physics Studies
- Astrophysics and Star Formation Studies
- Mass Spectrometry Techniques and Applications
- Molecular Spectroscopy and Structure
- Spectroscopy and Laser Applications
- Atmospheric Ozone and Climate
- Cold Atom Physics and Bose-Einstein Condensates
- Quantum, superfluid, helium dynamics
- Atomic and Subatomic Physics Research
- Ion-surface interactions and analysis
- Astro and Planetary Science
- Particle accelerators and beam dynamics
- X-ray Spectroscopy and Fluorescence Analysis
- Scientific Research and Discoveries
- Laser-Matter Interactions and Applications
- Nuclear Physics and Applications
- Stellar, planetary, and galactic studies
- Spectroscopy and Quantum Chemical Studies
- Laser-induced spectroscopy and plasma
- Advanced NMR Techniques and Applications
- X-ray Diffraction in Crystallography
- Crystallization and Solubility Studies
- Nuclear physics research studies
- Molecular spectroscopy and chirality
Max Planck Institute for Nuclear Physics
2015-2025
Columbia University
2008-2016
Weizmann Institute of Science
2016
Max Planck Society
2002-2015
University of Illinois Urbana-Champaign
2010-2015
Max Planck Institute for Astronomy
2012
UCLouvain
2010
Heidelberg University
2001-2010
Enercon (Germany)
2010
In chemistry and biology, chirality, or handedness, refers to molecules that exist in two spatial configurations are incongruent mirror images of one another. Almost all biologically active chiral, the correct determination their absolute configuration is essential for understanding development processes involving chiral molecules. Anomalous x-ray diffraction vibrational optical activity measurements broadly used determine solid liquid samples. Determining gas phase still a formidable...
During the epoch of first star formation, molecular hydrogen (H2) generated via associative detachment (AD) H- and H is believed to have been main coolant primordial gas for temperatures below 10(4) kelvin. The uncertainty in cross section this reaction has limited our understanding protogalaxy formation during characteristic masses cooling times stars. We report precise energy-resolved measurements AD reaction, made with use a specially constructed merged-beams apparatus. Our results agreed...
An electrostatic cryogenic storage ring, CSR, for beams of anions and cations with up to 300 keV kinetic energy per unit charge has been designed, constructed, put into operation. With a circumference 35 m, the ion-beam vacuum chambers all beam optics are in cryostat cooled by closed-cycle liquid helium system. At temperatures as low (5.5 ± 1) K inside time constants several minutes almost an hour were observed atomic molecular, anion cation at 60 keV. The intensity, energy-dependent...
We demonstrate that the dissociative recombination of ${\mathrm{D}}_{2}{\mathrm{H}}^{+}$ with low-energy electrons depends on rotational energy molecular ion such highly excited ions have a larger rate coefficient than colder ones. Observations an beam continuously interacting at low relative velocity indicate levels are preferentially depleted which, in competition radiative heating due to blackbody radiation, provides opportunity for controlling temperature stored molecules.
The energy-resolved rate coefficient for the dissociative recombination (DR) of $\mathrm{H}_{3}{}^{+}$ with slow electrons has been measured by storage-ring method using an ion beam produced from a radiofrequency multipole trap, employing buffer-gas cooling at 13 K. electron energy spread merged-beams measurement is reduced to $500\text{ }\text{ }\ensuremath{\mu}\mathrm{eV}$ cryogenic GaAs photocathode. This and previous cold-$\mathrm{H}_{3}{}^{+}$ jointly confirm capability storage rings,...
The excitation temperature T01 derived from the relative intensities of J = 0 (para) and 1 (ortho) rotational levels H2 has been assumed to be an accurate measure kinetic in interstellar environments. In diffuse molecular clouds, average value is ∼70 K. However, T(H+3) (J, K) (1, 1) 0) H+3 observed ∼30 K same types this work, we present observations three additional cloud sight lines for which measurements are available, showing that four five cases discrepant. We then examine thermalization...
Enhanced abundance of primordial HeH + Though only recently detected in space, the helium hydride ion (HeH ) is thought to be first molecule ever have formed early Universe. Novotný et al. report state-specific rate coefficients for dissociative reaction with electrons, obtained using a cryogenic storage ring combined merged electron beam (see Perspective by Bovino and Galli). They detect substantial rotational dependence decrease rates lowest states , far below values listed astrochemistry...
High-resolution dissociative recombination rate coefficients of rotationally cool and hot ${\mathrm{H}}_{3}^{+}$ in the vibrational ground state have been measured with a 22-pole trap setup Penning ion source, respectively, at storage-ring TSR. The experimental results are compared theoretical calculations to explore dependence coefficient on temperature study contributions different symmetries probe rich predicted resonance spectrum. kinetic energy release was investigated by fragment...
Photodetachment thermometry on a beam of OH− in cryogenic storage ring cooled to below 10 K is carried out using two-dimensional frequency- and time-dependent photodetachment spectroscopy over 20 min ion storage. In equilibrium with the low-level blackbody field, we find an effective radiative temperature near 15 about 90% all ions rotational ground state. We measure J=1 natural lifetime (about 193 s) determine transition dipole moment 1.5% uncertainty. also rotationally dependent relative...
We have studied the photodissociation of ${\mathrm{CH}}^{+}$ in Cryogenic Storage Ring at ambient temperatures below 10 K. Owing to extremely high vacuum cryogenic environment, we were able store beams with a kinetic energy $\ensuremath{\sim}60\text{ }\text{ }\mathrm{keV}$ for several minutes. Using pulsed laser, observed Feshbach-type near-threshold resonances rotational levels $J=0--2$ ${\mathrm{CH}}^{+}$, exclusively. In comparison updated, state-of-the-art calculations, find excellent...
We present a merged-beams study of reactions between <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:msup><a:mrow><a:mi>HD</a:mi></a:mrow><a:mrow><a:mo>+</a:mo></a:mrow></a:msup></a:mrow></a:math> ions, stored in the Cryogenic Storage Ring (CSR), and laser-produced ground-term C atoms. The molecular ions are for up to 20 s extreme vacuum CSR, where they have time relax radiatively until reach their vibrational ground state (within 0.5 storage) rotational...
Fragmentation patterns for dissociative recombination of the triatomic hydrogen molecular ion H(3)(+) in vibrational ground state have been measured using storage ring technique and fragment imaging. A broad distribution states H(2) after two-body dissociation a large predominance nearly linear momentum geometries three-body are found. The fragmentation results directly contrasted with Coulomb explosion imaging data on initial geometry, compared to existing wave-packet calculations,...
Infrared absorption spectroscopy of few hundred H3+ ions trapped in a 22-pole ion trap is presented using chemical probing as sensitive detection technique down to the single level. By exciting selected overtone transitions (v1=0,v2l=31)←(0,00) vibrational band an external cavity diode laser accurate diagnostics measurement effective translational and rotational temperatures was performed. The absolute accuracy measured transition frequencies improved by factor four compared previous plasma...
We have performed measurements of the dissociative electron recombination (DR) ${\mathrm{H}}_{3}^{+}$ at ion storage ring TSR utilizing a supersonic expansion source. The source has been characterized by continuous wave cavity ring-down spectroscopy. present high-resolution DR rate coefficients for different nuclear spin modifications combined with precise fragment imaging studies internal excitation ions inside ring. resolve changes in energy dependence between ortho-${\mathrm{H}}_{3}^{+}$...
The vibrational relaxation of ${\mathrm{H}}_{3}^{+}$ molecules from a conventional plasma ion source is studied performing Coulomb explosion imaging on the ions extracted storage ring after variable times storage. Storage for 2 s found sufficient radiative breathing excitation and fragment velocity distribution in coordinate then agrees well with simulations based calculated ground-state wave function. decay two lowest pure levels ${(1,0}^{0})$ ${(2,0}^{0})$ seen to be considerably faster...
The breakup dynamics of ${\mathrm{H}}_{3}^{+}$ and ${\mathrm{D}}_{3}^{+}$ following dissociative recombination is studied using the combination two-dimensional imaging storage ring techniques. vibrational distributions molecular ${\mathrm{H}}_{2}$ ${\mathrm{D}}_{2}$ fragments produced in two body fragmentation channel were measured, as well kinematical correlation between hydrogen or deuterium atoms three channel. For latter, we find predominantly linear dissociation geometries. data also...
The dissociative recombination (DR) of $^{3}\mathrm{He}\phantom{\rule{0.2em}{0ex}}^{4}\mathrm{He}^{+}$ has been investigated at the heavy-ion Test Storage Ring (TSR) in Heidelberg by observing neutral products from electron-ion collisions a merged beams configuration relative energies near-zero (thermal electron energy about 10 meV) up to 40 eV. After storage and cooling for 35 s, an effective DR rate coefficient...
We describe a simple gas expansion ion source based on static discharge voltages and commercially available pulsed valve. The is initiated by the pulse itself between two high voltage electrodes, without need for fast switches or complex timing schemes. very reliably produces intense bursts of molecular ions (with currents exceeding 100 μA during pulse-on phase) with only minor pulse-to-pulse variations in intensity shape. have characterized internal energy H3+ N2O+ produced source, using...
We have momentum-analyzed electrons and recoil ions in triple coincidence with projectiles neutralized 300-keV <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:mrow><a:mi mathvariant="normal">S</a:mi><a:msup><a:mrow><a:mi mathvariant="normal">i</a:mi></a:mrow><a:mo>−</a:mo></a:msup><a:mo>+</a:mo><a:mi>Ar</a:mi></a:mrow></a:math> collisions. The experiment was performed at a cryogenic ion storage ring an in-ring reaction microscope. Differential momentum distributions for detachment...
Using a merged-beam configuration, we have performed absolute measurements for the associative detachment reaction ${\mathrm{H}}^{\ensuremath{-}}+\mathrm{H}\ensuremath{\rightarrow}{\mathrm{H}}_{2}+{e}^{\ensuremath{-}}$. Our energy-resolved this process remove long-standing discrepancy between theory and experiment fundamental reaction. In particular, find excellent agreement with theoretical results which previously seemed to be ruled out by earlier experiments using flowing afterglow technique.
We report experimental and theoretical results for associative detachment (AD) of ${\mathrm{D}}^{\ensuremath{-}}+\mathrm{D}\ensuremath{\rightarrow}{\mathrm{D}}_{2}+{e}^{\ensuremath{-}}$. compare these data to our previously published ${\mathrm{H}}^{\ensuremath{-}}+\mathrm{H}\ensuremath{\rightarrow}{\mathrm{H}}_{2}+{e}^{\ensuremath{-}}$. The measurements show no significant isotope effect in the total cross section. This is be contrasted with work which has found a diatomic systems partial AD...
We have measured dissociative recombination of HCl+ with electrons using a merged beams configuration at the heavy-ion storage ring TSR located Max Planck Institute for Nuclear Physics in Heidelberg, Germany. present absolute rate coefficient collision energies from 0 to 4.5 eV. also developed new method deriving cross section measurements. Our approach does not suffer approximations made by previously used methods. The was transformed plasma electron temperature range T=10 5000 K. show that...
The chemistry in the diffuse interstellar medium (ISM) initiates gradual increase of molecular complexity during life cycle matter. A key molecule that enables build-up new bonds and molecules via proton donation is H. Its evolution tightly related to hydrogen thought be well understood. However, recent observations ortho para lines H2 H ISM showed a puzzling discrepancy nuclear spin excitation temperatures populations between these two species. H, unlike H2, seems out thermal equilibrium,...
We present state-selected measurements of rotational cooling and excitation rates CH^{+} molecular ions by inelastic electron collisions. The experiments are carried out at a cryogenic storage ring, making use monoenergetic beam matched velocity in combination with state-sensitive laser dissociation the for simultaneous monitoring level populations. Employing times up to 600 s, we create conditions where electron-induced J=0 ground state dominates over radiative relaxation, allowing...
We have performed chemical probing spectroscopy of H3+ ions trapped in a cryogenic 22-pole ion trap. The were buffer gas cooled to ∼55 K by collisions with helium and argon. Excitation states above the barrier linearity was achieved Ti:sapphire laser operated between 11 300 13 cm−1. Subsequent excited argon lead formation ArH+ that detected quadrupole mass spectrometer high sensitivity. report observation 17 previously unobserved transitions linearity. Comparison theoretical calculations...