Abstract
In this work we investigate interatomic electronic decay processes taking place in mixed argon-xenon clusters upon the inner-valence ionization of an argon center. We demonstrate that both interatomic Coulombic decay and electron-transfer mediated decay (ETMD) are important in larger rare gas clusters as opposed to dimers. Calculated secondary electron spectra are shown to depend strongly on the spin-orbit coupling in the final states of the decay as well as the presence of polarizable environment. It follows from our calculations that ETMD is a pure interface process taking place between the argon-xenon layers. The interplay of all these effects is investigated in order to arrive at a suitable physical model for the decay of inner-valence vacancies taking place in mixed ArXe clusters.
One of the authors (E.F.) gratefully acknowledges financial support by the Heidelberg Graduate College 850. K.G. gratefully acknowledges the financial support of the DFG (Forschergruppe “Intermolecular and interatomic Coulombic decay”).
I. INTRODUCTION
II. ASYMPTOTIC DESCRIPTION OF THE DECAY WIDTHS
A. Interatomic Coulombic decay
B. Electron transfer mediated decay
III. THE ArXe CLUSTER MODEL AND COMPUTATIONAL METHODOLOGY
IV. RESULTS AND DISCUSSION
V. CONCLUSIONS
Key Topics
- Energy transfer
- 13.0
- Cluster spectra
- 12.0
- Photons
- 11.0
- Electron transfer
- 10.0
- Polymers
- 10.0
Figures
The total system is split into subsystems S _{ 1 } and S _{ 2 }. The R _{ i } (i = 1, 2) point to the corresponding centers of mass (COMs) with respect to an arbitrary origin O. The x _{ i } as well as the r _{ i } describe the electron coordinates once with respect to O and once with respect to the COMs.
The total system is split into subsystems S _{ 1 } and S _{ 2 }. The R _{ i } (i = 1, 2) point to the corresponding centers of mass (COMs) with respect to an arbitrary origin O. The x _{ i } as well as the r _{ i } describe the electron coordinates once with respect to O and once with respect to the COMs.
ICD process in subsystems S _{ 1 } and S _{ 2 }. After creating an inner valence vacancy in S _{ 1 } the hole is filled by an outer-valance electron of S _{ 1 }. The excess energy is transferred to S _{ 2 } and is used to remove an outer-valence electron (ICD electron).
ICD process in subsystems S _{ 1 } and S _{ 2 }. After creating an inner valence vacancy in S _{ 1 } the hole is filled by an outer-valance electron of S _{ 1 }. The excess energy is transferred to S _{ 2 } and is used to remove an outer-valence electron (ICD electron).
ETMD3 process in subsystems S _{ 1 } and S _{ 2 } where the two atoms A and B participate in the electron transfer and are combined to S _{ 1 }. After inner valence ionization of A, the vacancy is filled by an electron from B in S _{ 1 }. The energy is transferred to C (S _{ 2 }) which is ionized and hereby emits the ETMD electron.
ETMD3 process in subsystems S _{ 1 } and S _{ 2 } where the two atoms A and B participate in the electron transfer and are combined to S _{ 1 }. After inner valence ionization of A, the vacancy is filled by an electron from B in S _{ 1 }. The energy is transferred to C (S _{ 2 }) which is ionized and hereby emits the ETMD electron.
Jacobi coordinates used for the geometric description of the trimer. Q is the distance between A and B, R the distance from the center of mass of AB to C and α the angle between the lines represented by Q and R.
Jacobi coordinates used for the geometric description of the trimer. Q is the distance between A and B, R the distance from the center of mass of AB to C and α the angle between the lines represented by Q and R.
Model system for the electronic decay processes: Argon atom on a xenon surface either located in a fcc (left) or hcp position (right).
Model system for the electronic decay processes: Argon atom on a xenon surface either located in a fcc (left) or hcp position (right).
Final state energies of the Ar^{+}/Xe^{+} fragment occurring after ICD for the possible total angular momenta. The intersections with the horizontal line representing the potential energy curve of the Ar (3s ^{−1}) initial state are the thresholds for the opening of the different ICD channels. These thresholds exhibit a significant dependence on the total angular momenta of the corresponding ions. For comparison the nonrelativistic final state is also shown leading to just one intersection point.
Final state energies of the Ar^{+}/Xe^{+} fragment occurring after ICD for the possible total angular momenta. The intersections with the horizontal line representing the potential energy curve of the Ar (3s ^{−1}) initial state are the thresholds for the opening of the different ICD channels. These thresholds exhibit a significant dependence on the total angular momenta of the corresponding ions. For comparison the nonrelativistic final state is also shown leading to just one intersection point.
Comparison of the relativistic and nonrelativistic ICD decay rates in the cluster model. The inset shows the relativistic and nonrelativistic ICD electron spectra for some pair in the cluster at a distance of R = 10.59 Å. The two relativistic peaks refer to the and channels. The other two are energetically not accessible. The nonrelativistic spectrum shows only one peak corresponding to the channel. To guide the eye of the reader we convoluted the spectra with Gaussian functions with FWHM of 0.3 eV (see text for discussion).
Comparison of the relativistic and nonrelativistic ICD decay rates in the cluster model. The inset shows the relativistic and nonrelativistic ICD electron spectra for some pair in the cluster at a distance of R = 10.59 Å. The two relativistic peaks refer to the and channels. The other two are energetically not accessible. The nonrelativistic spectrum shows only one peak corresponding to the channel. To guide the eye of the reader we convoluted the spectra with Gaussian functions with FWHM of 0.3 eV (see text for discussion).
Comparison of the relativistic and nonrelativistic ETMD decay rates in the cluster. To guide the eye of the reader we convoluted the spectra with Gaussian functions with FWHM of 0.6 eV (see text for discussion).
Comparison of the relativistic and nonrelativistic ETMD decay rates in the cluster. To guide the eye of the reader we convoluted the spectra with Gaussian functions with FWHM of 0.6 eV (see text for discussion).
Comparison of the relativistic and nonrelativistic ICD and ETMD decay widths. Note that the nonrelativistic spectrum shows clearly separated ICD and ETMD features. Taking into account the spin-orbit coupling leads to the appearance of a significant overlap between the peaks.
Comparison of the relativistic and nonrelativistic ICD and ETMD decay widths. Note that the nonrelativistic spectrum shows clearly separated ICD and ETMD features. Taking into account the spin-orbit coupling leads to the appearance of a significant overlap between the peaks.
Tables
Experimental single ionization energies (SIP) for the Ar and Xe atoms and their shifts Δ in homonuclear clusters.
Experimental single ionization energies (SIP) for the Ar and Xe atoms and their shifts Δ in homonuclear clusters.
Atomic parameters required for the calculation of ICD decay rates according to Eq. (18) . See text for the calculation of . The lifetimes and ionization cross sections for the spin-coupled case were taken from Refs. ^{ 50–52 } , respectively.
Atomic parameters required for the calculation of ICD decay rates according to Eq. (18) . See text for the calculation of . The lifetimes and ionization cross sections for the spin-coupled case were taken from Refs. ^{ 50–52 } , respectively.
Atomic and molecular parameters required for the calculation of the ETMD decay rates according to Eq. (21) . See text for the calculation of the and the transition dipole moments. The remaining parameters are again taken from the literature. ^{ 49–54 }
Atomic and molecular parameters required for the calculation of the ETMD decay rates according to Eq. (21) . See text for the calculation of the and the transition dipole moments. The remaining parameters are again taken from the literature. ^{ 49–54 }
Total decay widths and lifetimes of the ICD process.
Total decay widths and lifetimes of the ICD process.
Total decay widths and lifetimes of the ETMD process.
Total decay widths and lifetimes of the ETMD process.
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