| 1. |
- Hikosaka, Y., et al.
(författare)
-
X-ray absorption measured in the resonant Auger scattering mode
- 2008
-
Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 101:7
-
Tidskriftsartikel (refereegranskat)abstract
- We report both experimental and theoretical studies on x-ray absorption measured in the resonant Auger scattering mode of gas phase carbon monoxide near the O1s -> 2 pi region. Both experiment and theory display a crucial difference between the x-ray absorption profiles obtained in the conventional and resonant scattering modes. Lifetime vibrational interference is the main source of the difference. It is demonstrated that such interference, which arises from a coherent excitation to overlapping intermediate levels, ruins the idea for obtaining x-ray absorption spectra in a lifetime broadening free regime.
|
|
| 2. |
- Iwayama, H., et al.
(författare)
-
A local chemical environment effect in site-specific Auger spectra of ethyl trifluoroacetate
- 2013
-
Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 138:2, s. 024306-
-
Tidskriftsartikel (refereegranskat)abstract
- We have investigated a local chemical environment effect on Auger spectra of ethyl trifluoroacetate (C4H5F3O2), using multi-electron coincidence spectroscopy and high-resolution electron spectroscopy. Site-specific KVV Auger spectra for each carbon atom, and for the fluorine and oxygen atoms are presented. The extent of hole localization in the final dicationic states was investigated with the help of theoretical calculations based on a two-hole population analysis. The Auger spectra have been simulated using a statistical approach. It is found that all Auger decays populate mainly localized dicationic states, with the two holes located either on the same fluorine atom or on adjacent fluorine atoms. While the decay of the F 1s hole populates exclusively the former states, the latter class of states is also populated by the decay of the C and O 1s holes.
|
|
| 3. |
- Carniato, S., et al.
(författare)
-
Photon-energy dependence of single-photon simultaneous core ionization and core excitation in CO2
- 2016
-
Ingår i: PHYSICAL REVIEW A. - 2469-9926. ; 94:1
-
Tidskriftsartikel (refereegranskat)abstract
- We have studied the K-2V process corresponding to simultaneous K-shell ionization and K-shell excitation in the CO2 molecule. We define these K-2V states as super shake-up, at variance with the "conventional" K(-1)v(-1)V shake-up states. While the nature and evolution with photon energy of the conventional shake-up satellites has been the object of many studies, no such data on a large photon-energy range were previously reported on super shake-up. The CO2 molecule is a textbook example because it exhibits two well-isolated K-2V resonances (with V being 2 pi(u)* and 5 delta g*) with different symmetries resulting from shake-up processes of different origin populated in comparable proportions. The variation of the excitation cross section of these two resonances with photon energy is reported, using two different experimental approaches, which sheds light on the excitation mechanisms. Furthermore, double-core-hole spectroscopy is shown to be able to integrate and even expand information provided by conventional single-core-hole X-ray Photoelectron Spectroscopy (XPS) and Near-Edge X-ray Absorption Fine Structure (NEXAFS) techniques, revealing, for instance, g-g dipole forbidden transitions which are only excited in NEXAFS spectra through vibronic coupling.
|
|
| 4. |
- Eland, J. H. D., et al.
(författare)
-
Spectra of the triply charged ion CS[sub 2][sup 3+] and selectivity in molecular Auger effects
- 2010
-
Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 132:10, s. 104311-
-
Tidskriftsartikel (refereegranskat)abstract
- Spectra of triply charged carbon disulphide have been obtained by measuring, in coincidence, all three electrons ejected in its formation by photoionization. Measurements of the CS23+ ion in coincidence with the three electrons identify the energy range where stable trications are formed. A sharp peak in this energy range is identified as the 2Π ground state at 53.1±0.1 eV, which is the lowest electronic state according to ab initio molecular orbital calculations. Triple ionization by the double Auger effect is provisionally divided, on the basis of the pattern of energy sharing between the two Auger electrons into contributions from direct and cascade Auger processes. The spectra from the direct double Auger effect via S 2p, S 2s, and C 1s hole states contain several resolved features and show selectivity based on the initial charge localization and on the identity of the initial state. Triple ionization spectra from single Auger decay of S 2p -based core-valence states CS22+ show retention of the valence holes in this Auger process. Related ion-electron coincidence measurements give the triple ionization yields and the breakdown patterns in triple photoionization at selected photon energies from 90 eV to above the inner shell edges.
|
|
| 5. |
- Eland, J. H. D., et al.
(författare)
-
Spectra of the triply charged ion CS23+ and selectivity in molecular Auger effects
- 2010
-
Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 132:10, s. 104311-
-
Tidskriftsartikel (refereegranskat)abstract
- Spectra of triply charged carbon disulphide have been obtained by measuring, in coincidence, all three electrons ejected in its formation by photoionization. Measurements of the CS23+ ion in coincidence with the three electrons identify the energy range where stable trications are formed. A sharp peak in this energy range is identified as the (2)Pi ground state at 53.1 +/- 0.1 eV, which is the lowest electronic state according to ab initio molecular orbital calculations. Triple ionization by the double Auger effect is provisionally divided, on the basis of the pattern of energy sharing between the two Auger electrons into contributions from direct and cascade Auger processes. The spectra from the direct double Auger effect via S 2p, S 2s, and C 1s hole states contain several resolved features and show selectivity based on the initial charge localization and on the identity of the initial state. Triple ionization spectra from single Auger decay of S 2p-based core-valence states CS22+ show retention of the valence holes in this Auger process. Related ion-electron coincidence measurements give the triple ionization yields and the breakdown patterns in triple photoionization at selected photon energies from 90 eV to above the inner shell edges.
|
|
| 6. |
- Hikosaka, Y., et al.
(författare)
-
Energy Correlation of the Three Electrons Emitted during the Triple Photoionization of Ar
- 2009
-
Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 102:1, s. 013002-
-
Tidskriftsartikel (refereegranskat)abstract
- We report on an experimental investigation of energy correlation among three electrons emitted in valence triple photoionization (TPI) of Ar. The energy correlations reveal a predominant contribution from sequential TPI processes involving intermediate Ar2+ formation, which suggests that such indirect contributions should be included in the formulation of the threshold law for TPI cross sections. The differential cross section for direct TPI at about 150 eV above threshold producing one slow electron with a few eV kinetic energy is found to have a deeply hollow U-shaped profile in energy sharing between the other two electrons.
|
|
| 7. |
- Honda, Y., et al.
(författare)
-
DAP emission band in a carbon doped (1-101)GaN grown ob (001) Si substrate
- 2009
-
Ingår i: Phys. Stat. Sol. (c) Vol. 6. - : Wiley. ; , s. S772-S775
-
Konferensbidrag (refereegranskat)abstract
- Optical spectra of a C-doped (1-101) GaN are investigated via time resolved photoluminescence spectroscopy. Samples with different C-doping levels were prepared by metalorganic vapour phase epitaxy using C2H2 as the doping precursor. A carbon related emission peak is identified at 375 nm which shows typical behaviours for a donor-acceptor-pair emission band. The acceptor level is estimated to be 190 meV which is at 43 meV shallower than that in an Mg doped GaN. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
|
|
| 8. |
- Kumarathunge, Dushan P., et al.
(författare)
-
Acclimation and adaptation components of the temperature dependence of plant photosynthesis at the global scale
- 2019
-
Ingår i: New Phytologist. - : John Wiley & Sons. - 0028-646X .- 1469-8137. ; 222:2, s. 768-784
-
Tidskriftsartikel (refereegranskat)abstract
- The temperature response of photosynthesis is one of the key factors determining predicted responses to warming in global vegetation models (GVMs). The response may vary geographically, owing to genetic adaptation to climate, and temporally, as a result of acclimation to changes in ambient temperature. Our goal was to develop a robust quantitative global model representing acclimation and adaptation of photosynthetic temperature responses.We quantified and modelled key mechanisms responsible for photosynthetic temperature acclimation and adaptation using a global dataset of photosynthetic CO2 response curves, including data from 141 C3 species from tropical rainforest to Arctic tundra. We separated temperature acclimation and adaptation processes by considering seasonal and common-garden datasets, respectively.The observed global variation in the temperature optimum of photosynthesis was primarily explained by biochemical limitations to photosynthesis, rather than stomatal conductance or respiration. We found acclimation to growth temperature to be a stronger driver of this variation than adaptation to temperature at climate of origin.We developed a summary model to represent photosynthetic temperature responses and showed that it predicted the observed global variation in optimal temperatures with high accuracy. This novel algorithm should enable improved prediction of the function of global ecosystems in a warming climate.
|
|
| 9. |
- Mailhiot, M., et al.
(författare)
-
Search for the interatomic Auger effect in Nitrous Oxide
- 2023
-
Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - 0368-2048. ; 265
-
Tidskriftsartikel (refereegranskat)abstract
- The interatomic Auger effect following O 1s ionization in N2O has been experimentally investigated using multi-electron coincidence spectroscopy. The expected transition energies have been established by comparison to the measured N 1s−1v−1 core-valence double ionization energies. We describe a procedure to eliminate the background of two competing processes contributing spectroscopic signatures to the same energy range, namely double Auger decay of the O 1s vacancy and direct single-photon double ionization into the N 1s−1v−1 states. While the interatomic Auger transitions could not be successfully isolated, we provide an upper boundary of the transition probability of 0.07% with respect to the dominant single Auger decay after O 1s ionization.
|
|
