scispace - formally typeset
Search or ask a question
Journal Article•DOI•

Interatomic and intermolecular coulombic decay: The early years

Uwe Hergenhahn1•
Max Planck Society1
01 Apr 2011-Journal of Electron Spectroscopy and Related Phenomena (Elsevier)-Vol. 184, Iss: 3, pp 78-90
TL;DR: In weakly bonded matter, efficient autoionization channels have been found, in which not only the initially excited state, but also neighbouring atoms or molecules take part as discussed by the authors, which are known as Interatomic or Intermolecular Coulombic Decay (ICD).
About: This article is published in Journal of Electron Spectroscopy and Related Phenomena.The article was published on 2011-04-01 and is currently open access. It has received 132 citations till now. The article focuses on the topics: Interatomic Coulombic decay & Autoionization.

Summary (5 min read)

Jump to: [1. Introduction] – [1.1. An example -the Ne dimer] – [1.2. Theoretical Considerations] – [2. Experiments on noble gas clusters] – [2.1. ICD in Ne clusters] – [2.2. ICD in Ne Ar clusters] – [2.3. ICD of satellite states] – [2.3.1. ICD of satellite states, Ar] – [2.3.2. ICD of satellite states, Ne] – [2.3.3. ICD of satellite states, He] – [3. Experiments on water and solvents] – [3.1. ICD in water clusters] – [3.1.1. Investigating ICD by electron, electron coincidence techniques] – [3.1.2. ICD in medium sized water clusters] – [3.1.3. ICD in water dimers] – [3.2. ICD in solutions] – [4. Resonant ICD] – [4.1. Resonant ICD in solutions] – [5. Other non-local autoionization processes] and [6. Perspectives of the field]

1. Introduction

  • A vacancy site in an isolated atom or molecule can relax by flourescence, dissociation or-if energy permits-by autoionization.
  • Considering autoionization in particular, this can take place if the ionization energy used to produce the initial vacancy is above the double ionization threshold of the system.
  • It has long been known that the double ionization threshold of clusters is lower with respect to the monomer [1] .
  • A simple example will be used as an introduction into the topic in the next subsection, followed by some essential points from the theory of ICD.
  • Due to the limited space available it is not possible to give a complete review of the field here, and I apologize to all whose important works are not cited here.

1.1. An example -the Ne dimer

  • The first successful experiments on ICD in 2003 [7] and 2004 [8, 9] confirmed that the expected autoionization process indeed takes place.
  • The signature of ICD has been seen in all three steps described above:.

1.2. Theoretical Considerations

  • Like all autoionization processes, ICD is driven by the Coulomb interaction between the electrons involved in the transition.
  • The matrix element (2) factorizes into a direct and an exchange term, the former being associated with energy transfer between the two sites and the latter with charge transfer.
  • The ICD rate depends strongly on the spatial distance R between the two entities involved.
  • One may say it is shorthand for a certain matrix element resulting from Coulombic Interactions.
  • Decay depends strongly on the number of nearest neighbours.

2. Experiments on noble gas clusters

  • The noble gas clusters were not the first systems, for which ICD was predicted [2] .
  • From an experimental viewpoint they have the advantage of being prepared easily however.
  • This is done by expanding the noble gas through a conical nozzle into vacuum [18] .
  • Among the noble gas clusters, potential targets for the investigation of ICD are Ne clusters and mixed clusters of Ne and another noble gas.
  • In Ar clusters, simple inner valence (3s −1 ) vacancies are located below the double ionization threshold, but some satellite states can autoionize (see below).

2.1. ICD in Ne clusters

  • The low kinetic energy part of the electron spectrum of photoionized Ne clusters was recorded by the author and coworkers in 2003 [7] .
  • Jahnke et al., as mentioned above, used a COLTRIMS (Cold Target Recoil Ion Momentum Spectroscopy) spectrometer to detect in coincidence one of the electrons and both ions created by ICD of the Ne dimer [8] .
  • Using additionally an auxiliary magnetic field, slow electrons can be guided to a second detector opposite to the ion branch [24, 25] .
  • That is saying, total energy of the final state after ICD is a constant.

2.2. ICD in Ne Ar clusters

  • Mixed noble gas clusters constitute another class of interesting prototype systems for the research on ICD.
  • The reaction equation in this system reads EQUATION A simple estimate using atomic binding energies, Coulombic repulsion and the equilibrium distances of the respective neutral clusters (3.5 Å, [34] ) gives 7 eV.
  • The difference could be due to final state polarization in the experiment.
  • Two further aspects of this work are of interest: 1. Argon condenses much earlier than neon, and whether in a coexpansion of neon and argon mixed clusters or pure argon clusters seeded by atomic +Ar + final state is steeply repulsive, the nodal structure of the initial state reappears in the ICD spectrum.

2.3. ICD of satellite states

  • In the examples I have described so far, a single-hole inner valence vacancy state undergoes autoionization.
  • Besides these a large number of singly ionized states exist, which cannot be described as a single-hole configuration.
  • The latter is saying that the binding energy of a lot of satellite states is similar to inner-valence ionization energies; in fact most satellites are slightly higher in energy.
  • The question therefore arises whether these states can decay by ICD, too.
  • A number of beautiful works consider this problem, and I will summarize three of them below:.

2.3.1. ICD of satellite states, Ar

  • It is interesting that cations with some kinetic energy (0.75 eV) are observed at even lower photon energies, namely already above the Ar 3s ionization threshold (29.2 eV, [38] ).
  • The latter ion + excited neutral pair at the dimer equilibrium geometry is formed at a point on its potential curve lying 0.75 eV above the energetic minimum.
  • The two step process consisting of 3s ionization followed by energy transfer to a neighbouring atom and dissociation was in fact observed in larger.
  • Ar clusters before the first experimental report on ICD, and is somewhat reminiscent to it, the difference being that the 'other' atom is not ionized [39] .
  • Similar results on ICD of satellite states were also observed for Kr and Xe dimers [38] .

2.3.2. ICD of satellite states, Ne

  • In larger clusters they broaden as the excited electron changes its character from a Rydberg to an excitonic excitation [41] , but in dimers their binding energies do not change much.
  • The authors now consider explicitly the satellites in the binding energy interval [50, 58.5] eV.
  • As this requires a spatial overlap of the wavefunctions, the magnitude of the matrix element depends exponentially on the internuclear distance, and not just by a power law.
  • The decay can only proceed after the internuclear separation has reduced substantially.
  • The lower internuclear distance at the moment of ICD is reflected in a larger KER, which was the experimental fact that gave rise to the above interpretation.

2.3.3. ICD of satellite states, He

  • An extreme example for ICD has been observed in the decay of satellite states in the He dimer.
  • The Coulomb explosion characteristic for ICD nevertheless has been observed [43] .
  • A theoretical model again highlights the decisive role of nuclear dynamics in the decay [44] .

3. Experiments on water and solvents

  • The experiments described so far all had one thing in common:.
  • They were carried out on noble gas clusters.
  • These are prototypical for weakly bonded systems.
  • While ICD may lead to a rather confined spectral line in noble gas clusters, in molecular clusters it smears out to a quasi-continuum, even when nuclear dynamics is not influential.
  • Simple electron spectroscopy, such as in e.g. Ref.s [7, 35] , therefore so far did not deliver an unambiguous result.

3.1. ICD in water clusters

  • Eventually, two experiments on ICD in water clusters were successful [16, 15] .
  • If only the vertical ionization potentials are considered, the energetics for inner valence ICD in water cluster is not much different from noble gas clusters: (Earlier experiments gave 32.2 eV [74] and 32.6 eV [75] .).
  • Again, the single-site double vacancy states with energies of 37.98 eV and higher are above the inner valence ionization energy.
  • This is only possible by single photoionization followed by dissociation of the molecule (at least to some extent), and subsequent autoionization [79, 80] .

3.1.1. Investigating ICD by electron, electron coincidence techniques

  • In an experiment carried out in the group of the author, a magnetic bottle spectrometer was used for that purpose [81, 82, 27] .
  • One can then do a targeted experiment on the secondary electron spectrum attributed to inner valence photoionization (only) of water clusters.
  • This system has been discussed above (2.1) and the authors have seen an isolated ICD feature at kinetic energies of 1.2-1.6 eV (Fig. 3 ).
  • The minimum allowed total energy equals twice the ionization energy of the monomer.
  • Since the hemispherical electron analyzer used in earlier experiments [7, 22] had a strongly decreasing transmission function for electrons below one eV in kinetic energy, this was impossible to show at that time.

3.1.2. ICD in medium sized water clusters

  • Electron pairs having the ICD signature were indeed found in electronelectron coincidence spectra of free water cluster jets [16] (Fig. 7 ).
  • Mean cluster sizes of 45 and 200 molecules were investigated.
  • Several cross checks can be made to underpin the validity of the interpretation given:.
  • The result is a rather unstructured spectrum which is ascending towards very low electron energies (Fig. 7, a ) and in qualitative agreement with the predictions for small clusters [84] .
  • Electron pairs with a fixed total energy, appearing as diagonal lines in the coincidence plot, are indeed seen in high contrast plots of the coincident intensities.

3.1.3. ICD in water dimers

  • These authors recorded coincident events of two singly charged water cations with opposite momenta, and of two electrons (four particles were detected in coincidence).
  • Any reasonable candidate for a reaction that is foreclosing this channel should therefore invoke the electronic structure only to create the two distributed vacancies.
  • (As the experiment was carried out with synchrotron radiation, which is produced in the form of ps long pulses of low intensity, any two-photon processes in the ionization could be ruled out.).
  • 2 eV has been measured for the two water cations.
  • Meanwhile, the Coulomb explosion of the dimer has been simulated and the discrepancy could be explained from an unusual amount of rotational energy acquired by the ions during the dissociation [90] .

3.2. ICD in solutions

  • A suitable technique to probe solutions by electron spectroscopy, pioneered by Faubel and Winter [91] , uses a liquid jet injected under high pressure into vacuum.
  • Two studies relevant to ICD were carried out by this technique.
  • For a system consisting of a K + decorated with some H 2 O molecules, decay spectra were calculated, the above mentioned mixed vacancy states were shown to be significantly different in final state energy, and also in theory they are populated with an intensity of some % with respect to the main Auger channels.
  • The calculation of final state energies corroborates the assignment of the experimental feature identified with ICD-like channels.
  • This could not be asserted or disproven from the experiment.

4. Resonant ICD

  • Soon after the discovery of ICD, discussion of a resonant variant of this process started.
  • An inner valence vacancy is produced not by ionization but by excitation into some unoccupied orbital.
  • A theoretical account on resonant ICD has also been given, this time about MgNe after Ne 2s excitation [94] .

4.1. Resonant ICD in solutions

  • So far, I have discussed ICD after inner valence excitaton, which is following the original conceptual work.
  • Their binding energies can trivially be determined, as there is only one outgoing electron.
  • Moreover, from the electronic configuration of OH − [95] it is not obvious how a splitting into three states could occur.
  • An alternative, striking explanation has been found:.
  • It was further supposed that this energy transfer greatly gains in efficiency by orbital overlap between the OH − and the solvent shell.

5. Other non-local autoionization processes

  • Other autoionization schemes in loosely bound complexes were proposed from theory besides ICD.
  • Autoionization processes, in which the initial vacancy is not filled locally, but by electron transfer from a neighbouring atom or molecule, have been discussed using the term Electron Transfer Mediated Decay (ETMD) [96] .
  • In ETMD it ends up with one less unit of charge than before the decay, e.g. a singly charged vacancy after the decay is neutral.).
  • This is in line with experimental results on non-local autoionization of satellite channels, for which ICD vs. energy transfer is ruled out by selection rules [40] .
  • Electron Transfer Mediated Decay has also been mentioned as an ex-planation for the ionic fragment spectra of larger ArXe mixed clusters [100] .

6. Perspectives of the field

  • Experiments so far made on ICD fall mainly into one of two groups:.
  • The latter have revealed precise information on the energy and dynamics of ICD in small systems, while the former have Certainly, the authors are just beginning to explore the chemical diversity of ICD.
  • Another-yet visionary-application might be in solar cells:.
  • The main factor underlying these findings is the nature of the strongly electronegative ligands; in most other molecules, Auger decay is a mainly local process as stated above.
  • Charge exchange and energy transfer are central processes also in the diverse field of collision physics.

Did you find this useful? Give us your feedback

Citations
More filters
Journal Article•DOI•
Interatomic and intermolecular Coulombic decay: the coming of age story

[...]

Till Jahnke1•
Goethe University Frankfurt1
28 Apr 2015-Journal of Physics B
TL;DR: In this paper, Cederbaum et al. showed that ICD is a very general and common feature occurring after a manifold of excitation schemes and in numerous weakly bound systems, as revealed by more than 200 publications.
Abstract: In pioneering work by Cederbaum et al an excitation mechanism was proposed that occurs only in loosely bound matter (Cederbaum et al 1997 Phys Rev Lett 79 4778): it turned out, that (in particular) in cases where a local Auger decay is energetically forbidden, an excited atom or molecule is able to decay in a scheme which was termed ‘interatomic Coulombic decay’ (or ‘intermolecular Coulombic decay’) (ICD) As ICD occurs, the excitation energy is released by transferring it to an atomic or molecular neighbor of the initially excited particle As a consequence the neighboring atom or molecule is ionized as it receives the energy A few years later the existence of ICD was confirmed experimentally (Marburger et al 2003 Phys Rev Lett 90 203401; Jahnke et al 2004 Phys Rev Lett 93 163401; Ohrwall et al 2004 Phys Rev Lett 93 173401) by different techniques Since this time it has been found that ICD is not (as initially suspected) an exotic feature of van der Waals or hydrogen bonded systems, but that ICD is a very general and common feature occurring after a manifold of excitation schemes and in numerous weakly bound systems, as revealed by more than 200 publications It was even demonstrated, that ICD can become more efficient than a local Auger decay in some system This review will concentrate on recent experimental investigations on ICD It will briefly introduce the phenomenon and give a short summary of the ‘early years’ of ICD (a detailed view on this episode of investigations can be found in the review article by U Hergenhahn with the same title (Hergenhahn 2011 J Electron Spectrosc Relat Phenom 184 78)) More recent articles will be presented that investigate the relevance of ICD in biological systems and possible radiation damage of such systems due to ICD The occurrence of ICD and ICD-like processes after different excitation schemes and in different systems is covered in the middle section: in that context the helium dimer (He2) is a particularly interesting (and exotic) system in which ICD was detected It was employed in several publications to elucidate the strong impact of nuclear motion on ICD and its longrange-character The review will present these findings and their initial theoretical predictions and give insight into most recent time-resolved measurements of ICD

162 citations

Journal Article•DOI•
Calculating core-level excitations and X-ray absorption spectra of medium-sized closed-shell molecules with the algebraic-diagrammatic construction scheme for the polarization propagator.

[...]

Jan Wenzel1, Michael Wormit1, Andreas Dreuw1•
Interdisciplinary Center for Scientific Computing1
05 Oct 2014-Journal of Computational Chemistry
TL;DR: A variant of the algebraic‐diagrammatic construction scheme of second‐order ADC(2) is implemented by applying the core‐valence separation (CVS) approximation to the ADC( 2) working equations, providing access to properties of core‐excited states and allowing for the calculation of X‐ray absorption spectra.
Abstract: Core-level excitations are generated by absorption of high-energy radiation such as X-rays. To describe these energetically high-lying excited states theoretically, we have implemented a variant of the algebraic-diagrammatic construction scheme of second-order ADC(2) by applying the core-valence separation (CVS) approximation to the ADC(2) working equations. Besides excitation energies, the CVS-ADC(2) method also provides access to properties of core-excited states, thereby allowing for the calculation of X-ray absorption spectra. To demonstrate the potential of our implementation of CVS-ADC(2), we have chosen medium-sized molecules as examples that have either biological importance or find application in organic electronics. The calculated results of CVS-ADC(2) are compared with standard TD-DFT/B3LYP values and experimental data. In particular, the extended variant, CVS-ADC(2)-x, provides the most accurate results, and the agreement between the calculated values and experiment is remarkable. © 2014 Wiley Periodicals, Inc.

140 citations

Journal Article•DOI•
Site- and energy-selective slow-electron production through intermolecular Coulombic decay

[...]

Kirill Gokhberg1, Přemysl Kolorenč2, Alexander I. Kuleff1, Lorenz S. Cederbaum1•
Heidelberg University1, Charles University in Prague2
30 Jan 2014-Nature
TL;DR: The energy of the emitted electrons depends sensitively on the initial excited state of the argon atom, and the incident energy can be adjusted both to produce the initial excitation in a chosen atom and to realize an excitation that will result in the emission of ICD electrons with desired energies.
Abstract: Intermolecular Coulombic decay driven by resonant Auger decay can be used to produce low-energy electrons selectively from chosen molecular or atomic sites and with tunable energies, with possible applications in radiation therapy. The irradiation of matter with light tends to electronically excite atoms and molecules. What happens to the resulting excitation energy depends on the nature of the relaxation pathway and the energy of the electrons and ions produced. In one such pathway, known as intermolecular Coulombic decay (ICD), excess energy is transferred to neighbouring atoms or molecules that then lose an electron and become ionized. ICD electrons have relatively low energy, prompting suggestions that they might be harnessed as a form of Auger therapy — cancer treatment that uses large numbers of genotoxic low-energy electrons to damage cancer cells. In a pair of papers [in this issue of Nature] published online this week, Gokhberg et al. propose that ICD can be triggered upon relaxation of an initial resonant core excitation, and Trinter et al. confirm the existence of the proposed excitation experimentally. The efficiency of this relaxation cascade and the fact that it can be tuned to directly control the generation site and the energy of the electrons raise the prospect of the development of more targeted cancer radiotherapy, and possibly new spectroscopic techniques. Irradiation of matter with light tends to electronically excite atoms and molecules, with subsequent relaxation processes determining where the photon energy is ultimately deposited and electrons and ions produced. In weakly bound systems, intermolecular Coulombic decay1 (ICD) enables very efficient relaxation of electronic excitation through transfer of the excess energy to neighbouring atoms or molecules that then lose an electron and become ionized2,3,4,5,6,7,8,9. Here we propose that the emission site and energy of the electrons released during this process can be controlled by coupling the ICD to a resonant core excitation. We illustrate this concept with ab initio many-body calculations on the argon–krypton model system, where resonant photoabsorption produces an initial or ‘parent’ excitation of the argon atom, which then triggers a resonant-Auger-ICD cascade that ends with the emission of a slow electron from the krypton atom. Our calculations show that the energy of the emitted electrons depends sensitively on the initial excited state of the argon atom. The incident energy can thus be adjusted both to produce the initial excitation in a chosen atom and to realize an excitation that will result in the emission of ICD electrons with desired energies. These properties of the decay cascade might have consequences for fundamental and applied radiation biology and could be of interest in the development of new spectroscopic techniques.

123 citations

Journal Article•DOI•
Analysis and comparison of CVS-ADC approaches up to third order for the calculation of core-excited states

[...]

Jan Wenzel1, Andre Holzer1, Michael Wormit1, Andreas Dreuw1•
Interdisciplinary Center for Scientific Computing1
03 Jun 2015-Journal of Chemical Physics
TL;DR: The extended second order algebraic-diagrammatic construction (ADC(2)-x) scheme for the polarization operator in combination with core-valence separation (CVS) approximation is well known to be a powerful quantum chemical method for the calculation of core-excited states and the description of X-ray absorption spectra.
Abstract: The extended second order algebraic-diagrammatic construction (ADC(2)-x) scheme for the polarization operator in combination with core-valence separation (CVS) approximation is well known to be a powerful quantum chemical method for the calculation of core-excited states and the description of X-ray absorption spectra. For the first time, the implementation and results of the third order approach CVS-ADC(3) are reported. Therefore, the CVS approximation has been applied to the ADC(3) working equations and the resulting terms have been implemented efficiently in the adcman program. By treating the α and β spins separately from each other, the unrestricted variant CVS-UADC(3) for the treatment of open-shell systems has been implemented as well. The performance and accuracy of the CVS-ADC(3) method are demonstrated with respect to a set of small and middle-sized organic molecules. Therefore, the results obtained at the CVS-ADC(3) level are compared with CVS-ADC(2)-x values as well as experimental data by calculating complete basis set limits. The influence of basis sets is further investigated by employing a large set of different basis sets. Besides the accuracy of core-excitation energies and oscillator strengths, the importance of cartesian basis functions and the treatment of orbital relaxation effects are analyzed in this work as well as computational timings. It turns out that at the CVS-ADC(3) level, the results are not further improved compared to CVS-ADC(2)-x and experimental data, because the fortuitous error compensation inherent in the CVS-ADC(2)-x approach is broken. While CVS-ADC(3) overestimates the core excitation energies on average by 0.61% ± 0.31%, CVS-ADC(2)-x provides an averaged underestimation of −0.22% ± 0.12%. Eventually, the best agreement with experiments can be achieved using the CVS-ADC(2)-x method in combination with a diffuse cartesian basis set at least at the triple-ζ level.

103 citations

Journal Article•DOI•
On the nature and origin of dicationic, charge-separated species formed in liquid water on X-ray irradiation.

[...]

Stephan Thürmer1, Milan Ončák1, Niklas Ottosson1, Robert Seidel2, Uwe Hergenhahn2, Stephen E. Bradforth1, Petr Slavíček1, Bernd Winter1 •
Helmholtz-Zentrum Berlin1, Max Planck Society2
01 Jul 2013-Nature Chemistry
TL;DR: This work elucidate the ultrafast proton dynamics in the first few femtoseconds after X-ray core-level ionization of liquid water and shows through isotope analysis of the Auger spectra that proton-transfer dynamics occur on the same timescale as electron autoionization.
Abstract: To understand the yield and patterns of damage in aqueous condensed matter, including biological systems, it is essential to identify the initial products subsequent to the interaction of high-energy radiation with liquid water. Until now, the observation of several fast reactions induced by energetic particles in water was not possible on their characteristic timescales. Therefore, some of the reaction intermediates involved, particularly those that require nuclear motion, were not considered when describing radiation chemistry. Here, through a combined experimental and theoretical study, we elucidate the ultrafast proton dynamics in the first few femtoseconds after X-ray core-level ionization of liquid water. We show through isotope analysis of the Auger spectra that proton-transfer dynamics occur on the same timescale as electron autoionization. Proton transfer leads to the formation of a Zundel-type intermediate [HO*···H···H2O]+, which further ionizes to form a so-far unnoticed type of dicationic charge-separated species with high internal energy. We call the process proton-transfer mediated charge separation. Previously unobserved types of reactive species formed on the core ionization of liquid water have been identified using a combination of liquid microjet photoemission spectroscopy and ab initio calculations. The charge-separated di-cationic species are formed within a few femtoseconds, through proton-transfer-mediated processes followed by autoionization.

102 citations

References
More filters
Journal Article•DOI•
Resonant Formation of DNA Strand Breaks by Low-Energy (3 to 20 eV) Electrons

[...]

Badia Boudaïffa1, Pierre Cloutier1, Darel J. Hunting1, Michael A. Huels1, Léon Sanche1 •
Université de Sherbrooke1
03 Mar 2000-Science
TL;DR: It is shown that reactions of such electrons, even at energies well below ionization thresholds, induce substantial yields of single- and double-strand breaks in DNA, which are caused by rapid decays of transient molecular resonances localized on the DNA's basic components.
Abstract: Most of the energy deposited in cells by ionizing radiation is channeled into the production of abundant free secondary electrons with ballistic energies between 1 and 20 electron volts. Here it is shown that reactions of such electrons, even at energies well below ionization thresholds, induce substantial yields of single- and double-strand breaks in DNA, which are caused by rapid decays of transient molecular resonances localized on the DNA's basic components. This finding presents a fundamental challenge to the traditional notion that genotoxic damage by secondary electrons can only occur at energies above the onset of ionization, or upon solvation when they become a slowly reacting chemical species.

1,891 citations

Book•
Atomic and Molecular Beam Methods

[...]

Giacinto Scoles
01 Jan 1988
TL;DR: In this paper, the authors present an overview of the general principles and methods for surface scattering of atoms in visible and UV spectroscopy, including a detailed discussion of the basic principles of surface scattering.
Abstract: Part I: Spectroscopy. 1: Spectroscopy of molecular beams: an overview. 2: Magnetic and electric resonance spectroscopy. 3: Beam-maser spectroscopy. 4: Quantum amplifiers and oscillators. 5: Metrology with molecular beams. 6: Infrared laser spectroscopy. 7: Visible and UV spectroscopy: physical aspects. 8: Photofragment spectroscopy. 9: Fourier-transform microwave spectroscopy. 10: Fourier-transform methods: infrared. Part II: Surface Scattering. 11: General principles and methods. 12: Elastic scattering of atoms. 13: Rotational inelastic scattering. 14: Single phonon inelastic helium scattering. 15: Multiple phonon inelastic scattering. 16: Scattering from disordered surfaces. 17: Reactive scattering

1,739 citations

Journal Article•DOI•
Recoil-ion and electron momentum spectroscopy: reaction-microscopes

[...]

Joachim Ullrich1, R. Moshammer1, Alexander Dorn1, Reinhard Dörner1, L. Ph. H. Schmidt, Horst Schmidt-Böcking1 •
Max Planck Society1
13 Aug 2003-Reports on Progress in Physics
TL;DR: In this article, the authors present a comprehensive set of FDCSs for single ionization of atoms by ion-impact, the most basic atomic fragmentation reaction, brought new insight, a couple of surprises and unexpected challenges to theory at keV to GeV collision energies.
Abstract: Recoil-ion and electron momentum spectroscopy is a rapidly developing technique that allows one to measure the vector momenta of several ions and electrons resulting from atomic or molecular fragmentation. In a unique combination, large solid angles close to 4π and superior momentum resolutions around a few per cent of an atomic unit (a.u.) are typically reached in state-of-the art machines, so-called reaction-microscopes. Evolving from recoil-ion and cold target recoil-ion momentum spectroscopy (COLTRIMS), reaction-microscopes—the `bubble chambers of atomic physics'—mark the decisive step forward to investigate many-particle quantum-dynamics occurring when atomic and molecular systems or even surfaces and solids are exposed to time-dependent external electromagnetic fields. This paper concentrates on just these latest technical developments and on at least four new classes of fragmentation experiments that have emerged within about the last five years. First, multi-dimensional images in momentum space brought unprecedented information on the dynamics of single-photon induced fragmentation of fixed-in-space molecules and on their structure. Second, a break-through in the investigation of high-intensity short-pulse laser induced fragmentation of atoms and molecules has been achieved by using reaction-microscopes. Third, for electron and ion-impact, the investigation of two-electron reactions has matured to a state such that the first fully differential cross sections (FDCSs) are reported. Fourth, comprehensive sets of FDCSs for single ionization of atoms by ion-impact, the most basic atomic fragmentation reaction, brought new insight, a couple of surprises and unexpected challenges to theory at keV to GeV collision energies. In addition, a brief summary on the kinematics is provided at the beginning. Finally, the rich future potential of the method is briefly envisaged.

1,375 citations

Journal Article•DOI•
Time-resolved atomic inner-shell spectroscopy

[...]

Markus Drescher1, Markus Drescher2, M. Hentschel1, Reinhard Kienberger1, M. Uiberacker1, Vladislav S. Yakovlev1, Armin Scrinzi1, Th. Westerwalbesloh2, Ulf Kleineberg2, Ulrich Heinzmann2, Ferenc Krausz1 •
Vienna University of Technology1, Bielefeld University2
24 Oct 2002-Nature
TL;DR: It is demonstrated that a laser-based sampling system, consisting of a few-femtosecond visible light pulse and a synchronized sub-feminine soft X-ray pulse, allows us to trace the relaxation dynamics of core-excited atoms directly in the time domain with attosecond resolution.
Abstract: The characteristic time constants of the relaxation dynamics of core-excited atoms have hitherto been inferred from the linewidths of electronic transitions measured by continuous-wave extreme ultraviolet or X-ray spectroscopy. Here we demonstrate that a laser-based sampling system, consisting of a few-femtosecond visible light pulse and a synchronized sub-femtosecond soft X-ray pulse, allows us to trace these dynamics directly in the time domain with attosecond resolution. We have measured a lifetime of 7.9(-0.9)(+1.0) fs of M-shell vacancies of krypton in such a pump-probe experiment.

1,204 citations

Journal Article•DOI•
Long-Range Resonance Energy Transfer in Molecular Systems

[...]

Gregory D. Scholes1•
University of Toronto1
28 Nov 2003-Annual Review of Physical Chemistry
TL;DR: This review covers Förster theory for donor-acceptor pairs and electronic coupling for singlet-singlet, triplet-triplet, and superexchange-mediated energy transfer and includes the transition density picture of Coulombic coupling as well as electronic coupling between molecular aggregates (excitons).
Abstract: The current state of understanding of molecular resonance energy transfer (RET) and recent developments in the field are reviewed. The development of more general theoretical approaches has uncovered some new principles underlying RET processes. This review brings many of these important new concepts together into a generalization of Forster's original theory. The conclusions of studies investigating the various approximations in Forster theory are summarized. Areas of present and future activity are discussed. The review covers Forster theory for donor-acceptor pairs and electronic coupling for singlet-singlet, triplet-triplet, and superexchange-mediated energy transfer. This includes the transition density picture of Coulombic coupling as well as electronic coupling between molecular aggregates (excitons). Spectral overlaps and ensemble energy transfer rates in disordered aggregates, the role of dielectric properties of the medium, weak versus strong coupling, and new models for energy transfer in complex molecular assemblies are also described.

1,097 citations

Related Papers (5)
Giant Intermolecular Decay and Fragmentation of Clusters

[...]

15 Dec 1997-Physical Review Letters
Lorenz S. Cederbaum, J. Zobeley, Francesco Tarantelli
Experimental evidence for interatomic coulombic decay in Ne clusters.

[...]

23 May 2003-Physical Review Letters
Simon Marburger, Oliver Kugeler, Uwe Hergenhahn, Thomas Möller 
Interatomic and intermolecular Coulombic decay: the coming of age story

[...]

28 Apr 2015-Journal of Physics B
Till Jahnke
Ultrafast energy transfer between water molecules

[...]

01 Feb 2010-Nature Physics
Till Jahnke, H. Sann, T. Havermeier, K. Kreidi, C. Stuck, M. Meckel, Markus Schöffler, N. Neumann, R. Wallauer, S. Voss, Achim Czasch, Ottmar Jagutzki, A. Malakzadeh, F. Afaneh, Th. Weber, Horst Schmidt-Böcking, Reinhard Dörner 
Experimental Observation of Interatomic Coulombic Decay in Neon Dimers

[...]

13 Oct 2004-Physical Review Letters
Till Jahnke, Achim Czasch, Markus Schöffler, S. Schössler, A. Knapp, M. Käsz, J. Titze, C. Wimmer, K. Kreidi, Robert E. Grisenti, André Staudte, Ottmar Jagutzki, Uwe Hergenhahn, Horst Schmidt-Böcking, Reinhard Dörner 
Frequently Asked Questions (1)
Q1. What are the contributions mentioned in the paper "Interatomic and intermolecular coulombic decay: the early years" ?

The author summarizes the experimental research on ICD up to the presence. An outlook on other non-local autoionization processes and on future directions of ICD research closes the article.