Showing papers by "Yasumasa Hikosaka published in 2015"
TL;DR: A theoretical model that provides absolute cross sections for simultaneous core-ionization core-excitation (K(-2)V) and its predictions with experimental results obtained on the water molecule after photoionization by synchrotron radiation are compared.
Abstract: We present in detail a theoretical model that provides absolute cross sections for simultaneous core-ionization core-excitation (K−2V ) and compare its predictions with experimental results obtained on the water molecule after photoionization by synchrotron radiation. Two resonances of different symmetries are assigned in the main K−2V peak and comparable contributions from monopolar (direct shake-up) and dipolar (conjugate shake-up) core-valence excitations are identified. The main peak is observed with a much greater width than the total experimental resolution. This broadening is the signature of nuclear dynamics.
33 citations
TL;DR: In this article, the authors give an outlook on the basis of recently published results, of the complementarity of these light sources for double core-hole spectroscopy, with a prospective of what could be done in the future with the technical breakthrough that will be necessary to improve our further understanding of chemical analysis.
26 citations
TL;DR: The formalism developed in the companion Paper I is used here for the interpretation of spectra obtained recently on the nitrogen molecule, and the evolution with photon energy of the relative contribution of shake- up and conjugate shake-up processes is discussed.
Abstract: The formalism developed in the companion Paper I is used here for the interpretation of spectra obtained recently on the nitrogen molecule. Double core-hole ionization K−2 and core ionization-core excitation K−2V processes have been observed by coincidence electron spectroscopy after ionization by synchrotron radiation at different photon energies. Theoretical and experimental cross sections reported on an absolute scale are in satisfactory agreement. The evolution with photon energy of the relative contribution of shake-up and conjugate shake-up processes is discussed. The first main resonance in the K−2V spectrum is assigned to a K−2π∗ state mainly populated by the 1s→ lowest unoccupied molecular orbital dipolar excitation, as it is in the K−1V NEXAFS (Near-Edge X-ray Absorption Fine Structure) signals. Closer to the K−2 threshold Rydberg resonances have been also identified, and among them a K−2σ∗ resonance characterized by a large amount of 2s/2p hybridization, and double K−2(2σ∗/1π/3σ)−11π∗2 shake-up...
25 citations
07 Sep 2015
TL;DR: In this paper, the authors demonstrate ultrafast multiphoton coherent excitation in near-infrared intense laser fields (≤10 TW/cm2) using excited helium in the 1s2p (1P) state as the target.
Abstract: We demonstrate ultrafast multiphoton coherent excitation in near-infrared intense laser fields (≤10 TW/cm2) using excited helium in the 1s2p (1P) state as the target. Strong two-photon coupling between the 2p state and the 5f and 6f Rydberg states drives ultrafast Rabi oscillations in tens of femtosecond. Theoretical calculations solving the time-dependent Schrodinger equation were carried out to elucidate the strong field effects.
07 Sep 2015
TL;DR: In this article, the simultaneous core ionization and core excitation process induced by absorption of a single photon provides the basis of a new spectroscopy that offers both advantages of X-ray Photoelectron Spectroscopy (XPS) and near-edge x-ray absorption fine structures (NEXAFS) spectrograms.
Abstract: The simultaneous core ionization and core excitation process (or K-2V process) induced by absorption of a single photon provides the basis of a new spectroscopy that offers both advantages of X-ray Photoelectron Spectroscopy (XPS) and near-edge x-ray absorption fine structures (NEXAFS) spectroscopy