Near-threshold behavior of theK-shell satellites in CO

Abstract

The study of photoelectron satellites in the near-threshold region is important for differentiating among various electron correlation mechanisms. For CO, which is a prominent test case for theories describing electron correlation effects, the threshold and near-threshold branching ratios (BR s) of the K-shell satellites were measured. Eight different C 1s satellite states were identified, showing very complex threshold behavior. The resonancelike behavior of the {20. ) '(1n. ) '(2~)'(5'=1) satellite BR agrees with recent theoretical calculations.The observed energy dependence of the singlet (2o. ) '(1m) '(2m. *)' satellite compares less well with the calculations. Three X+ satellites with a (2o. ) '(50 ) '(no. )' configuration have a constant satellite BR over the energy range studied. Three 20.satellites, which have been assigned as pure conjugate shake-up states, have intensity only near threshold. The threshold spectrum above the 0 1s ionization threshold consists of two distinct groups of satellites. Conjugate shake-up transitions contribute to the intense feature centered at 551-eV binding energy, which is not observed above its threshold. Two 'X+ satellites, which have been described by configuration interaction of (1') '(50. ) '(no. )' states with a singlet mm. * state, show indications of shape-resonance-like behavior.PACS number(s): 33.60. Fy, 33.80.b

Development of symmetry-resolved zero-kinetic-energy photoelectron spectroscopy for probing multielectron processes

“…The first ZEKE spectra in the K-shell excitation regions were measured by Medhurst et al for N 2 and CO. 3 Later, Reich et al investigated the photoelectron satellites in the nearthreshold region of CO by using a threshold time-of-flight analyzer to detect energetic photoelectrons as well as ZEKE electrons. 4 The symmetries of the inner-shell excited states of small molecules can be deduced from the information obtained by the angle-resolved photoion spectroscopic ͑ARPIS͒ technique. This involves angularly resolved measurement of the fragment-ion emission with respect to the polarization direction of synchrotron radiation.…”

The influence of valence excitations on spectral distribution of vibrational excitations associated with C 1s photoionization in the CO molecule

“…Their relative intensities are taken from the work [11]. Their spectroscopic parameters are respectively taken from the work [16] and extracted from the experimental line shape [11]. The distribution computed with the coupling (grey histograms) and without it (black ones) are plotted in Figure 3.…”

“…(5) and (6) to take into account the coupling of molecular vibrations with the shake-up S 0 ð 2 R þ Þ and S 1 ð 2 R þ Þ excitations. Their relative intensities are taken from the work [11]. Their spectroscopic parameters are respectively taken from the work [16] and extracted from the experimental line shape [11].…”

“…We suppose that the recent results reported for the N 1s ionization in NO [9] could be attributed, at least partly, to the non-FC effect under study. The conjugate shake-up excitations [11][12][13][14][15][16] and the internal inelastic photoelectron scattering on valence electrons [18,20] influence on the distribution of vibrational excitations too. The both processes lead to the core-ionized-valence-excited states intense near the threshold.…”

“…The final shake-up states 2r À1 1p À1 2p 1 ð 2 R þ Þ appear as the satellite excitations S 0 and S 1 in the C 1s photoelectron spectra [11][12][13][14][15][16]. The S 0 and S 1 are well known singlet-and triplet-coupled pp à -excitations located 14.9 and 8.3 eV above the C 1s À1 single-hole state, respectively.…”