| 1. |
- Nagaya, K., et al.
(författare)
-
Formation of the energetic doubly charged ne ion by irradiation of large neon clusters using intense EUV-FEL pulses at 52 nm
- 2010
-
Ingår i: Journal of Physics: Conference Series. - : Institute of Physics (IOP). - 1742-6596.
-
Konferensbidrag (refereegranskat)abstract
- The interaction of clusters with intense EUV-FEL pulses was investigated using the SPring-8 Compact SASE Source (SCSS) test facility in Japan. Neon clusters of mean sizes = 1000 and 4000 were irradiated by intense FEL pulses at 52 nm and emitted ions were detected by a momentum imaging spectrometer. The production of energetic doubly charged ions was not found for Ne 1000, but it was observed for Ne 4000 clusters, which suggests that an inhomogeneous charge distribution is generated for the larger clusters.
|
|
| 2. |
- Nagaya, K., et al.
(författare)
-
Unusual under-threshold ionization of neon clusters studied by ion spectroscopy
- 2013
-
Ingår i: Journal of Physics B. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 46:16 SI
-
Tidskriftsartikel (refereegranskat)abstract
- We carried out time-of-flight mass spectrometry for neon clusters that were exposed to intense free electron laser pulses with the wavelength of 62 nm, which induce optical transition from the ground state (2s(2) 2p(6)) to an excited state (2s(2) 2p(5) nl) in the Ne atoms. In contrast to Ne+ ions produced by two-photon absorption from isolated Ne atoms, the Ne+ ion yield from Ne clusters shows a linear dependence on the laser intensity (I). We discuss the ionization mechanisms which give the linear behaviour with respect to I and expected features in the electron emission spectrum.
|
|
| 3. |
- Sugishima, A., et al.
(författare)
-
Charge and energy transfer in argon-core-neon-shell clusters irradiated by free-electron-laser pulses at 62 nm
- 2012
-
Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 86:3, s. 033203-
-
Tidskriftsartikel (refereegranskat)abstract
- The multiple ionization of Ar-core-Ne-shell clusters in intense extreme-ultraviolet laser pulses (lambda similar to 62 nm) from the free-electron laser in Japan was investigated utilizing a momentum imaging technique. The Ar composition dependence of the kinetic energies and the yields of the fragment ions give evidence for charge transfer from the Ar core to the Ne shell. We have extended the uniformly charged sphere model originally applied to pristine clusters [Islam et al., Phys. Rev. A 73, 041201 (R) (2006)] to the core-shell heterogeneous clusters to estimate the amounts of charge and energy transfers.
|
|
| 4. |
- Yamada, A., et al.
(författare)
-
Ion-ion coincidence studies on multiple ionizations of N-2 and O-2 molecules irradiated by extreme ultraviolet free-electron laser pulses
- 2010
-
Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 132:20, s. 204305-
-
Tidskriftsartikel (refereegranskat)abstract
- We have investigated multiple ionization of N-2 and O-2 molecules by 52 nm extreme-ultraviolet light pulses at the free-electron laser facility SCSS in Japan. Coulomb break-up of parent ions with charge states up to 5+ is found by the ion-ion coincidence technique. The charge-state dependence of kinetic energy release distributions suggests that the electrons are emitted sequentially in competition with the elongation of the bond length.
|
|
| 5. |
- Nagaya, K., et al.
(författare)
-
Multiple photoionization of rare-gas clusters by EUV-FEL at Spring-8
- 2012
-
Ingår i: Journal of Physics, Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 388:3, s. 032082-
-
Tidskriftsartikel (refereegranskat)abstract
- Multiple photoionization processes of giant rare-gas clusters are investigated in the wavelength region of 51 to 61nm at Spring8. We report here some latest results of our investigation; the frustration of photoionization for giant xenon clusters and the charge transfer in Ar-core Ne-shell clusters.
|
|
| 6. |
- 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.
|
|
| 7. |
- Iwayama, H., et al.
(författare)
-
Different Time Scales in the Dissociation Dynamics of Core-Excited CF4 by Two Internal Clocks
- 2017
-
Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 119:20
-
Tidskriftsartikel (refereegranskat)abstract
- Fragmentation processes following C 1s -> lowest unoccupied molecular orbital core excitations in CF4 have been analyzed on the ground of the angular distribution of the CF3+ emitted fragments by means of Auger electron-photoion coincidences. Different time scales have been enlightened, which correspond to either ultrafast fragmentation, on the few-femtosecond scale, where the molecule has no time to rotate and the fragments are emitted according to the maintained orientation of the core-excited species, or dissociation after resonant Auger decay, where the molecule still keeps some memory of the excitation process before reassuming random orientation. Potential energy surfaces of the ground, core-excited, and final states have been calculated at the ab initio level, which show the dissociative nature of the neutral excited state, leading to ultrafast dissociation, as well as the also dissociative nature of some of the final ionic states reached after resonant Auger decay, yielding the same fragments on a much longer time scale.
|
|
| 8. |
- Piancastelli, Maria Novella, et al.
(författare)
-
Ultrafast dynamics in C 1s core-excited CF4 revealed by two-dimensional resonant Auger spectroscopy
- 2013
-
Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 138:23, s. 234305-
-
Tidskriftsartikel (refereegranskat)abstract
- Following core excitation in an isolated molecule, ultrafast dissociation of one particular chemical bond can occur, where "ultrafast" is defined as taking place during the lifetime of the core hole, of the order of few femtoseconds. The signature of such phenomenon can be observed in resonant Auger spectra following core excitation. We present here an investigation of ultrafast dissociation following C 1s-to-sigma* core excitation in CF4, with high-resolution resonant Auger spectroscopy. We are able to characterize final states of both the molecular ion and the CF3+ fragment. We use two-dimensional (2D) maps to record resonant Auger spectra across the resonance as a function of photon energy and to characterize ultrafast dynamics. This method provides immediate visual evidence of one of the important characteristics of the study of spectral features related to molecular versus fragment ionic final states, and namely their dispersion law. In the 2D maps we are also able to identify the dissociation limit for one of the molecular final states.
|
|
