H. Cederquist
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View article: Recurrent Fluorescence of Polycyclic Aromatic Hydrocarbon Isomers: A Comparative Study
Recurrent Fluorescence of Polycyclic Aromatic Hydrocarbon Isomers: A Comparative Study Open
Time-dependent unimolecular dissociation rates of the C12H8 isomers acenaphthylene (ACY) and biphenylene (BPY) cations were measured using a cryogenic electrostatic ion beam storage ring. The neutral, cyano-functionalized tracers of ACY, b…
View article: Electron Affinities of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi mathvariant="normal">C</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>60</mml:mn> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi mathvariant="normal">C</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>70</mml:mn> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> and Cooling of Their Anions
Electron Affinities of and and Cooling of Their Anions Open
We combine cryogenic storage of fullerene anions up to minutes with laser photo-detachment spectroscopy and measure the electron affinities to be 2.684(3) eV for C 60 and 2.7665(3) eV for C 70 , which settle long-standing issues co…
View article: Radiative Stabilization of the Indenyl Cation: Recurrent Fluorescence in a Closed-Shell Polycyclic Aromatic Hydrocarbon
Radiative Stabilization of the Indenyl Cation: Recurrent Fluorescence in a Closed-Shell Polycyclic Aromatic Hydrocarbon Open
Several small polycyclic aromatic hydrocarbons (PAHs) with closed-shell electronic structure have been identified in the cold, dark environment Taurus Molecular Cloud 1. We measure efficient radiative cooling through the combination of rec…
View article: Radiative cooling of the deprotonated cyan fluorescent protein chromophore anion
Radiative cooling of the deprotonated cyan fluorescent protein chromophore anion Open
An electrospray ion source has been coupled to a cryogenic electrostatic ion-beam storage ring to enable experimental studies of the fundamental properties of biomolecular ions and their reactions in the gas phase on longer timescales than…
View article: Radiative stabilization of the indenyl cation: Recurrent fluorescence in a closed-shell polycyclic aromatic hydrocarbon
Radiative stabilization of the indenyl cation: Recurrent fluorescence in a closed-shell polycyclic aromatic hydrocarbon Open
Several small polycyclic aromatic hydrocarbons (PAHs) with closed-shell electronic structure have been identified in the cold, dark environment Taurus Molecular Cloud-1. We measure efficient radiative cooling through the combination of rec…
View article: Dissociation and radiative stabilization of the indene cation: The nature of the C-H bond and astrochemical implications
Dissociation and radiative stabilization of the indene cation: The nature of the C-H bond and astrochemical implications Open
Indene (C$_9$H$_8$) is the only polycyclic pure hydrocarbon identified in the interstellar medium to date, with an observed abundance orders of magnitude higher than predicted by astrochemical models. The dissociation and radiative stabili…
View article: Elucidating the role of a molecular anion in mutual neutralisation reactions
Elucidating the role of a molecular anion in mutual neutralisation reactions Open
We have studied the MN of NO+ with NO2- under single-collision conditions at a collision energy of ≈0.1 eV. Combining cryogenically stored-and-merged ion beams with coincident-product imaging, we determine that the reaction predominantly p…
View article: Mutual neutralization of C<sub>60</sub><sup>+</sup> and C<sub>60</sub><sup>−</sup> ions
Mutual neutralization of C<sub>60</sub><sup>+</sup> and C<sub>60</sub><sup>−</sup> ions Open
Context . Mutual neutralization (MN) between cations and anions plays an important role in determining the charge balance in certain astrophysical environments. However, empirical data for such reactions involving complex molecular species…
View article: Mutual neutralization of C$_{60}^+$ and C$_{60}^-$ ions: Excitation energies and state-selective rate coefficients
Mutual neutralization of C$_{60}^+$ and C$_{60}^-$ ions: Excitation energies and state-selective rate coefficients Open
Context: Mutual neutralization between cations and anions play an important role in determining the charge-balance in certain astrophysical environments. However, empirical data for such reactions involving complex molecular species has be…
View article: Disentangling vibrationally-dependent molecular dynamics in mutual neutralisation reactions
Disentangling vibrationally-dependent molecular dynamics in mutual neutralisation reactions Open
Products and dynamics of mutual neutralisation (MN) reactions involving even simple molecular ions are largely unknown. Combining cryogenically stored-and-merged ion beams with coincident product-imaging addresses this issue.Application to…
View article: Cooling of gold cluster anions, Au$_N^-$, $N=2-13,15$, in a cryogenic ion-beam storage ring
Cooling of gold cluster anions, Au$_N^-$, $N=2-13,15$, in a cryogenic ion-beam storage ring Open
We have measured the spontaneous and photo-induced decays of anionic gold clusters, Au$_N^-$, with sizes ranging from $N = 2$ to 13, and 15. After production in a sputter ion source, the size-selected clusters were stored in the cryogenic …
View article: Stability of C<sub>59</sub> Knockout Fragments from Femtoseconds to Infinity
Stability of C<sub>59</sub> Knockout Fragments from Femtoseconds to Infinity Open
We have studied the stability of C 59 anions as a function of time, from their formation on femtosecond timescales to their stabilization on second timescales and beyond, using a combination of theory and experiments. The fragments…
View article: Precision measurements on Si-
Precision measurements on Si- Open
High-precision measurements of the electron affinities (EA) of the three stable isotopes of silicon, $^{28}$Si, $^{29}$Si and $^{30}$Si, have been performed at the cryogenic electrostatic ion-beam storage ring DESIREE. The quantum states o…
View article: Stability of C$_{59}$ Knockout Fragments from Femtoseconds to Infinity
Stability of C$_{59}$ Knockout Fragments from Femtoseconds to Infinity Open
We have studied the stability of C$_{59}$ anions as a function of time, from their formation on femtosecond timescales to their stabilization on second timescales and beyond, using a combination of theory and experiments. The C$_{59}^-$ fr…
View article: Near-infrared absorption and radiative cooling of naphthalene dimers (C<sub>10</sub>H<sub>8</sub>)<sub>2</sub>
Near-infrared absorption and radiative cooling of naphthalene dimers (C<sub>10</sub>H<sub>8</sub>)<sub>2</sub> Open
Time-dependent blue shift of action spectra in storage rings are used to determine the radiative cooling rate of naphthalene dimer cations, (C 10 H 8 ) 2 + . DFTB-EXCI and Monte-Carlo models are successful in reproducing infrared cooling t…
View article: Observation of an isotope effect in state-selective mutual neutralization of lithium with hydrogen
Observation of an isotope effect in state-selective mutual neutralization of lithium with hydrogen Open
We report on mutual neutralization measurements between 7Li+ and 1H- at effective center-of-mass collision energies in the range of 100 to 350 meV. We find that final states of lithium with principal quantum number n = 3 dominate with 3s s…
View article: Fragmentation of and electron detachment from hot copper and silver dimer anions: A comparison
Fragmentation of and electron detachment from hot copper and silver dimer anions: A comparison Open
We measured the spontaneous decays of internally hot copper and silver dimer anions, ${\mathrm{Cu}}_{2}^{\ensuremath{-}}$ and ${\mathrm{Ag}}_{2}^{\ensuremath{-}}$, stored in one of the two ion-beam storage rings of the Double Electrostatic…
View article: Efficient stabilization of cyanonaphthalene by fast radiative cooling and implications for the resilience of small PAHs in interstellar clouds
Efficient stabilization of cyanonaphthalene by fast radiative cooling and implications for the resilience of small PAHs in interstellar clouds Open
After decades of searching, astronomers have recently identified specific Polycyclic Aromatic Hydrocarbons (PAHs) in space. Remarkably, the observed abundance of cyanonaphthalene (CNN, C 10 H 7 CN) in the Taurus Molecular Cloud (TMC-1) is …
View article: Efficient radiative cooling of tetracene cations C<sub>18</sub>H<sub>12</sub><sup>+</sup>: absolute recurrent fluorescence rates as a function of internal energy
Efficient radiative cooling of tetracene cations C<sub>18</sub>H<sub>12</sub><sup>+</sup>: absolute recurrent fluorescence rates as a function of internal energy Open
High recurrent fluorescence rates of tetracene cations, C 18 H 12 , measured with two electrostatic ion rings, DESIREE and Mini-Ring, lead to much more effective radiative cooling than previously investigated PAH cations.
View article: Experimental radiative cooling rates of a polycyclic aromatic hydrocarbon cation
Experimental radiative cooling rates of a polycyclic aromatic hydrocarbon cation Open
The radiative cooling rate of cationic 1-cyanonaphthalene is determined from storage ring experiments and shown to be consistent with recurrent fluorescence. The rapid cooling helps explain the abundance of the neutral molecule in molecula…
View article: Radiative cooling of polyyne anions: C4H− and C6H−
Radiative cooling of polyyne anions: C4H− and C6H− Open
Time-dependent photodetachment action spectra for the linear hydrocarbon anions C4H− and C6H− are investigated using the cryogenic Double ElectroStatic Ion Ring ExpEriment. The radiative cooling characteristics of these ions on the millise…
View article: Resilience of small PAHs in interstellar clouds: Efficient stabilization of cyanonaphthalene by fast radiative cooling
Resilience of small PAHs in interstellar clouds: Efficient stabilization of cyanonaphthalene by fast radiative cooling Open
After decades of speculation and searching, astronomers have recently identified specific Polycyclic Aromatic Hydrocarbons (PAHs) in space. Remarkably, the observed abundance of cyanonaphthalene (CNN, C10H7CN) in the Taurus Molecular Cloud…
View article: Survival of polycyclic aromatic hydrocarbon knockout fragments in the interstellar medium
Survival of polycyclic aromatic hydrocarbon knockout fragments in the interstellar medium Open
Laboratory studies play a crucial role in understanding the chemical nature of the interstellar medium (ISM), but the disconnect between experimental timescales and the timescales of reactions in space can make a direct comparison between …
View article: Mutual neutralisation of O<sup>+</sup> with O<sup>−</sup>: investigation of the role of metastable ions in a combined experimental and theoretical study
Mutual neutralisation of O<sup>+</sup> with O<sup>−</sup>: investigation of the role of metastable ions in a combined experimental and theoretical study Open
The mutual neutralisation of O + with O − has been studied in a double ion-beam storage ring with combined merged-beams, imaging and timing techniques.
View article: Radiative cooling of carbon cluster anions C2n+1− (n = 3–5)
Radiative cooling of carbon cluster anions C2n+1− (n = 3–5) Open
Radiative cooling of carbon cluster anions C 2n+1 − ( n = 3–5) is investigated using the cryogenic electrostatic ion storage ring DESIREE. Two different strategies are applied to infer infrared emission on slow (milliseconds to seconds) an…
View article: Spontaneous Electron Emission from Hot Silver Dimer Anions: Breakdown of the Born-Oppenheimer Approximation
Spontaneous Electron Emission from Hot Silver Dimer Anions: Breakdown of the Born-Oppenheimer Approximation Open
We report the first experimental evidence of spontaneous electron emission from a homonuclear dimer anion through direct measurements of Ag_{2}^{-}→Ag_{2}+e^{-} decays on milliseconds and seconds timescales. This observation is very surpri…