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Vibrationally resolved spectra have been obtained for the lowest-lying cationic states X 2B1, A 2A1, and B 2B2 of the water molecule reached after participator resonant Auger decay of core-excited states. The angular distribution has been measured of the first four vibrational components of the X state in the photon energy regions including the O 1s→4a1 and the O 1s→2b2 core excitations, and for different portions of the vibrational envelope of the B state in the photon energy region including the O 1s→2b2 core excitation. For the X state, a large relative spread in β values of the different vibrational components is observed across both resonances. For the B state, a very different trend is observed for the high binding energy side and the low binding energy side of the related spectral feature as a function of photon energy. A theoretical method based on the scattering K matrix has been used to calculate both the photoabsorption spectrum and the β values, by taking both interference between direct and resonant photoemission and vibrational/lifetime interference into account. The numerical results show qualitative agreement with the trends detected in the experimental values and explain the conspicuous variations of the β values primarily in terms of coupling between direct and resonant photoemission by interaction terms of different sign for different final vibrational states. [ABSTRACT FROM AUTHOR]

The O and C 1s photoelectron satellites for the CO2 molecule fixed in space parallel to the electric vector of the incident radiation E are found to be more intense, in general, than those perpendicular to E and are enhanced at the photon energy in the vicinity of the shape resonance for the single-hole ionization cross section. This suggests that the excitation of the valence electron may be caused by the internal inelastic scattering of a primary 1s photoelectron with a valence electron. [Copyright &y& Elsevier]

Abstract: We have developed an ultra-fast multi-hit TDC to improve the momentum resolution in the multiple coincidence momentum imaging spectroscopy. The TDC consists of 12 bit/100 MHz crystal oscillator counters and seven time-to-amplitude converters. The TDC receives signals up to 6 as start pulses and one signal as a stop signal. The time resolution of the TDC is about 120 ps under the time span of 40  s. Using the present TDC, we have obtained the vibrational-resolved core-level photoelectron momentum distribution of CO molecules in coincidence with two fragment ions. [Copyright &y& Elsevier]