| 1. |
- Bao, Zhuo, et al.
(författare)
-
Detailed Theoretical and Experimental Description of Normal Auger Decay in O2
- 2008
-
Ingår i: Journal of Physics B. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 41:12, s. 125101-
-
Tidskriftsartikel (refereegranskat)abstract
- The normal Auger electron spectrum of the O-2 molecule is assigned in detail on the basis of ab initio valence configuration interaction (CI) wavefunctions. Potential energy curves of the ground state, the core-ionized states and the doubly charged final states are calculated and Auger decay rates are obtained with the one-centre approximation. Using the lifetime vibrational interference method, band shapes are obtained for all contributions to the Auger spectrum. The calculated Auger electron spectrum allows us to identify all features observed experimentally. Significant differences to previous assignments are reported. A quantitative simulation of the spectrum is given on the basis of a curve-fitting procedure, in which the energetic positions and intensities of the theoretical bands were optimized. Besides providing a basis for a refined analysis of the spectrum, the fit allows us to assess the accuracy of the calculation. As expected for this level of theory, the absolute accuracy of the valence CI energies is found to be about 0.3 eV. The inherent error of the one-centre transition rates is less than 5% of the most intense transition in the spectrum. The frequently questioned one-centre Auger transition rates are shown to be rather appropriate if applied with reasonable wavefunctions and if the vibrational band structure of the molecular spectrum is properly taken into account.
|
|
| 2. |
|
|
| 3. |
- Fink, Reinhold, et al.
(författare)
-
Specific production of very long-lived core-excited sulfur atoms by 2p(-1)sigma* excitation of the OCS molecule followed by ultrafast dissociation
- 2006
-
Ingår i: Journal of Physics B. - 0953-4075 .- 1361-6455. ; 39:12, s. L269-L275
-
Tidskriftsartikel (refereegranskat)abstract
- A core-excited sulfur state with a lifetime almost one order of magnitude longer than in molecular 2p core-hole states is selectively produced by ultrafast dissociation of S 2p -> sigma* excited OCS. Clear evidence for this is provided by strong atomic peaks (20% of the total intensity) in x-ray fluorescence but very weak ones (2%) in the corresponding resonant Auger spectrum. Corroborating the assignment of the spectra, ab initio calculations explain the enhanced lifetime: the Auger decay of the produced D-3(3) (2p(5)3p(5)) sulfur state is strongly decreased as it contradicts a newly derived propensity rule of the L2,3MM Auger decay.
|
|
| 4. |
- Ganguly, Smita, et al.
(författare)
-
Coincidence study of core-ionized adamantane: Site-sensitivity within a carbon cage?
- 2022
-
Ingår i: Physical chemistry chemical physics : PCCP. - 1463-9084. ; 24:47, s. 28994-29003
-
Tidskriftsartikel (refereegranskat)abstract
- We investigate the fragmentation dynamics of adamantane dications produced after core-ionization at the carbon edge followed by Auger decay. The combination of high-resolution electron spectroscopy, energy-resolved electron-ion multi-coincidence spectroscopy and different theoretical models allows us to give a complete characterization of the processes involved after ionization. We show that energy- and site-sensitivity is observed even for a highly-symmetric molecule that lacks any unique atomic site.
|
|
| 5. |
- Travnikova, Oksana, et al.
(författare)
-
Assignment of the L2,3VV normal Auger decay spectrum of Cl-2 by ab initio calculations
- 2009
-
Ingår i: Chemical Physics Letters. - : Elsevier BV. - 0009-2614 .- 1873-4448. ; 474:1-3, s. 67-73
-
Tidskriftsartikel (refereegranskat)abstract
- Auger decay processes of the Cl 2p ionized states have been studied in Cl-2 by means of high- resolution electron spectroscopy and ab initio calculations. This led to reassignment of the normal L2,3VV Auger decay spectrum of Cl2. The reliability of this assignment is strongly supported by an independent measurement of the L2; 3VV Auger electron spectrum of Cl2 which has been obtained after selective Cl 2p(3/2)(-1) photoionization of the chlorine molecule. Partial Auger transition rates for the three nongenerate spin-orbit and molecular- field- split 2p(-1) states - 2p(3/2,3/2)(-1) ((2)Pi(3/2)), 2p(3/2,1/2)(-1)((2)Sigma(+)(1/2)) and 2p(1/2,1/2)(-1)((2)Pi(1/2)) - show differences similar to the ones reported in previous works for HCl.
|
|
| 6. |
- Travnikova, Oksana, et al.
(författare)
-
Disentangling the complex line profiles in the Cl 2p photoelectron spectra of Cl-2
- 2006
-
Ingår i: Chemical Physics Letters. - : Elsevier BV. - 0009-2614 .- 1873-4448. ; 426:4-6, s. 452-458
-
Tidskriftsartikel (refereegranskat)abstract
- High-resolution Cl (2p) photoelectron spectra Of Cl-2 are reported and their complex structure is analyzed in detail, taking into account molecular field (NIF), spin-orbit (SO) and parity splitting. High-level ab initio calculations were performed to provide reliable values for spectroscopic parameters. Accurate data analysis enabled us to determine the value of molecular-field splitting of 86 7 meV, and values of 92 5, 79 11 and 105 12 meV for the lifetime line widths of the (2)Pi(1/2), (2)Sigma(+)(1/2) and (2)Pi(3/2) states, respectively. The gerade-ungerade splitting of less than 5 meV is obtained from the calculations.
|
|
| 7. |
- Velkov, Yasen, 1980-
(författare)
-
Quantum nuclear dynamics in x-ray scattering and lasing
- 2008
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis presents a theoretical study of the role of nuclear degrees of freedom in the x-ray absorption, x-ray resonant scattering and some aspects of the interaction of matter with strong laser fields. Most numerical simulations are performed with a time-dependent wave-packet program that have proved its robustness in previous investigations. The relevant experimental results are also presented for comparison when available. The first problem considered in the thesis is the possibility of obtaining x-ray absorption spectra with resolution beyond the natural lifetime broadening of the core-excited electronic states. It is shown that the method of measuring x-ray absorptionin the resonant scattering mode suggested earlier for that purpose exhibits severe limitations originating from the lifetime vibrational interference between the intermediate core-excited vibrational levels. However, a broad class of molecules is found for which spectra with super-high resolution can indeed be obtained. These molecules have parallel potential energy surfaces of the core-excited and final states for the x-ray scattering process. The interpretations of two interesting cases of x-ray absorption and Auger scattering follow. The first one is related to scattering through a doubly excited Π state in the CO molecule. A Doppler split feature near 299.4 eV and strong scattering anisotropy are observed. Both features are well explained and reproduced by the theory. Next, theelectron-vibrational fine structure of the excitation for O2 is investigated by means of different models. We are able to single out the electronic states and interpotential crossing points responsible for the peculiar absorption profile. Based on these findings we explain and reproduce the x-ray Auger scattering spectra through the same excitation. Here we encounter a rather unusual situation in which the Auger spectra are affected by three types of the interference: Apart from the lifetime vibrational interference, a strong interference between two intermediate electronic states and an interference with the direct-scattering amplitude is also present. The process of intramolecular vibrational redistribution (IVR) is investigated in the context of formation of amplified spontaneous emissions (ASE) inside laser-pumped gain media. IVR raises to a higher energy region the threshold pump intensity after which blue-shifted ASE is observed. Finally, we suggest a new scheme of x-ray pump-probe spectroscopy based on the core-hole hopping in N2 induced by an infrared laser field. We investigate the result from the core-hole hoping on the vibrational structure of the x-ray absorption profile. Furthermore, by populating core-excited states with opposite parities, the laser field opens up symmetry forbidden resonant inelastic scattering channels, which can give new insights about the electronic structure of matter.
|
|
| 8. |
|
|
