Misato Kazama

C 1s photoelectron angular distributions from fixed-in-space CO molecules in the high-energy continuum ≥50 eV

We measured molecular-frame photoelectron angular distributions (MFPADs) for a carbon 1s level of CO molecules in the kinetic energy range of up to 150 eV. X-ray photoelectron diffraction (XPD) theory was adopted to interpret the profiles of the MFPADs. Computational experiments within the framework of XPD theory were performed to demonstrate the emergence of interference effects between the direct photoelectron and scattered waves in the MFPAD profiles.

Recoil frame photoelectron angular distributions of BF3: a sensitive probe of the shape resonance in the F 1s continuum.

Recoil frame photoelectron angular distributions (RFPADs) of BF(3) molecules are presented over the energy region of the shape resonance in the F 1s continuum. Time-dependent density functional theory calculations are also given to understand the shape resonance dynamics. The RFPADs have been compared with the theoretical calculations. It is found that the RFPADs calculated by the localized core-hole model are in better agreement with the experimental, compared with those by the delocalized core hole. Dipole matrix elements and dipole prepared continuum wavefunctions show that the shape resonance in the F 1s ionization continuum of BF(3) is induced by p-partial waves as previously reported by Swanson et al. [J. Chem. Phys. 75, 619 (1981)]. However, due to the couplings with the other partial waves the feature characteristic of the p-partial waves has not been observed in the RFPADs.

Theoretical study of focusing and double slit effects in x-ray photoelectron diffraction

Double-slit and forward focusing effects in XPD spectra from H2O and GeCl2 molecules have been theoretically studied within the single scattering approximation. In low-and intermediate-energy region, the double-slit effect can be observed. In contrast, this effect wears off and only forward focusing peaks with simple structure are given in high-energy region. The double-slit effects can be observed under special conditions where the two scattering amplitudes have finite overlap in the bisecting direction.

Geometrical effect on the issue of asymmetric C 1s photoelectron angular distributions detected in coincidence with the fragment ion pairs of CO+?O+?for CO2?molecules

We have measured C 1s photoelectron angular distributions (PADs) in coincidence with the CO+–O+ fragment ion pairs of CO2 molecules at the photoelectron energies of 85, 120 and 150 eV. The observed left–right asymmetric PADs have been well reproduced by our theoretical model taking into account the two degenerate zero-point bending vibrations. This leads to a conclusive result on the interpretation of such PADs; although it has been believed so far that they are the molecular frame, in fact they are the recoil frame.

Low kinetic energy photoelectron diffractions for C 1s and O 1s electrons of free CO molecules in the EXAFS region

We have measured molecular-frame photoelectron angular distributions from carbon 1s and oxygen 1s levels of CO molecules up to a photoelectron kinetic energy (KE) of ~150 eV. The backward-scattering intensities exhibited a strong modulation as a function of the kinetic energy of the photoelectrons, whereas the intensities for the forward-scattering gradually increased and then became nearly constant over KE ~100 eV. Multiple scattering calculations with a muffin-tin potential qualitatively reproduced the experimental results. The present results may be considered as the observation of low-energy photoelectron diffraction patterns for gaseous free CO molecules, which are involved in modulations in extended X-ray absorption fine structure (EXAFS) spectra.