Effect of copper addition on precipitation behavior near grain boundary in Al-Zn-Mg alloy

Matsuda, Kenji*; Yasumoto, Toru*; Bendo, A.*; Tsuchiya, Taiki*; Lee, S.*; Nishimura, Katsuhiko*; Nunomura, Norio*; Marioara, C. D.*; Lervik, A.*; Holmestad, R.*; et al.

Materials Transactions, 60(8), p.1688 - 1696, 2019/08

https://doi.org/10.2320/matertrans.L-M2019828

no abstracts in English

Fluorescence decay processes following resonant 2p photoexcitation of Ar atoms and clusters studied using a time-resolved fluorescence and photoion coincidence technique

Gejo, Tatsuo*; Ikegami, Takeshi*; Homma, Kenji*; Harries, J.; Tamenori, Yusuke*

Journal of Physics B; Atomic, Molecular and Optical Physics, 46(7), p.075102_1 - 075102_9, 2013/04

https://doi.org/10.1088/0953-4075/46/7/075102

Dissociation and recapture dynamics in HO following O 1s inner-shell excitation

Gejo, Tatsuo*; Oura, Masaki*; Kuniwake, Miki*; Homma, Kenji*; Harries, J.

Journal of Physics; Conference Series, 288, p.012023_1 - 012023_7, 2011/04

https://doi.org/10.1088/1742-6596/288/1/012023

In this paper we present a study of the dissociation dynamics following O 1s inner-shell excitation/ionization in the water molecule. When the O 1s electron is excited just below or just above the ionization threshold, neutral fragments are created. Information on the electronic states of these fragments provides information on the dissociation dynamics. Excitation of the O 1s electron creates a HO ionic core, which is unstable and undergoes Auger decay. The resulting HO ion core subsequently dissociates into 2 or three fragments, to one of which the initially excited electron attaches. If this fragment is O or OH, a neutral, excited O atom can be created. This fragment can undergo further Auger (autoionisation) decay. Here we have analysed the kinetic energy distribution of both these low energy electrons and also the initial high energy Auger electron, obtaining new information on the processes involved.

Survey on present status and trend of parallel programming environments

Takemiya, Hiroshi*; Higuchi, Kenji; *; *; *; Imamura, Toshiyuki; ;

JAERI-Review 97-005, 105 Pages, 1997/03

JAERI-Review-97-005.pdf:4.67MB

no abstracts in English

Production of neutral particles following O 1s excitation of HO; H yield and kinetic energy, and ion-H coincidence studies

Harries, J.; Iseda, Mitsuhiro*; Kuniwake, Miki*; Homma, Kenji*; Gejo, Tatsuo*; Sullivan, J. P.*; Azuma, Yoshiro*

no journal, , 

We report here on studies where metastable H atoms and VUV photons are detected following the O 1s excitation of HO. The studies reveal new information not accessible with ion or electron techniques. The studies are performed using pulsed soft X-ray synchrotron radiation at SPring-8's BL27SU. Metastable particles and VUV photons are directly detected using 2 MCP detectors, and the arrival times of the particles are recorded relative both to each other and to the pulses of incoming radiation. The technique allows the separation of VUV and metastable particle yield, and the study of fluorescence lifetimes. The time-resolved detection of Lyman- radiation allows the determination of the population distribution of excited H atoms.

The Ionisation dynamics of water following oxygen 1s inner-shell excitation

Kuniwake, Miki*; Homma, Kenji*; Gejo, Tatsuo*; Asakura, Yuka*; Harries, J.

no journal, , 

When a molecule is irradiated with soft X-rays, an inner-shell electron is excited, leading to the creation of inner-shell vacancy states. De-excitation occurs via processes such as Auger decay and fluorescence. Water is a simple 3-atom molecule, and while its inner-shell excitation processes have been widely studied, there have been few studies on its photo-ionisation dissociation dynamics. Earlier work at SPring-8 revealed the importance of the production of neutral particles in this excitation region. In order to study in detail the production mechanism for metastable atoms, we have compared the kinetic energies of the metasable atoms with those of H ions, and found that they have different excitation photon energy dependencies.

The Decay routes of argon clusters studied using time-resolved fluorescence

Gejo, Tatsuo*; Iseda, Mitsuhiro*; Homma, Kenji*; Harries, J.; Tamenori, Yusuke*

no journal, , 

When a cluster undergoes inner-shell excitation, as well as electrons and ions fluorescence photons can also be detected. Depending on the excited state, the lifetime of this fluorescence is different, and so recording the arrival times of the photons relative to the exciting radiation, information can be obtained on the excited state distribution. This technique has previously been applied to the helium atom and water molecule, and is applied to clusters for the first time here. For argon clusters there are broadly two lifetime components, and their origin is discussed.

Photodissociation dynamics of water in K-edge energy region

Gejo, Tatsuo*; Kuniwake, Miki*; Homma, Kenji*; Harries, J.; Oura, Masaki*; Sullivan, J. P.*; Azuma, Yoshiro*

no journal, , 

Exciting an inner-shell electron of a molecule to just-above or just-below its ionisation limit provides a system where the Born-Oppenheimer principle is no longer valid, and a valuable opportunity for studying the interaction of the unstable ion core and a low-energy electron. When the ion core undergoes Auger decay and fragments, the initially excited electron can be recaptured. It is the aim of this research to understand what happens in the case of the water molecule, by (1) detecting excited H atoms produced when the electron is captured by an outgoing proton. (2) detect the Lyman- radiation produced when these excited H atoms decay, and (3) analysing the energy of low-energy Auger electrons emitted when the electron is captured by an O or O fragment.

The Photodissociation dynamics of HO after recapture process via Auger decay of O 1s inner-shell excitation

Gejo, Tatsuo*; Oura, Masaki*; Kuniwake, Miki*; Homma, Kenji*; Harries, J.

no journal, , 

In this research we have obtained new information on the photo-dissociation dynamics of the water molecule following O (1s) inner-shell excitation/ionisation. When the O 1s electron is excited as well as neutral excited H atoms, highly-excited O and OH fragments can also be produced. By investigating which states these fragments are in information can be obtained on the dissociation routes. When the inner-shell O 1s electron is excited/ionised, an HO ion core is formed. This is unstable, and Auger decay occurs. The resulting HO ion core dissociates, and one of the fragments can capture the initially excited electron. When this fragment is O, a neutral O atom is formed. This fragment can undergo further Auger decay, resulting in the production of an electron with low kinetic energy. In this research these electrons are detected and energy analysed.