Alignment of photoions far from threshold

Abstract

We present results of measurements and calculations of the alignment for CO+(B 2Σ+) photoions over an extended energy range (0≤Ek≤210 eV). The polarization of CO+(B 2Σ+→X 2Σ+) fluorescence indicates that the photoions retain significant alignment even at high energies. Agreement between the measured and calculated polarization of the fluorescence is excellent.

Photoion rotational distributions from near-threshold to deep in the continuum

“…9,22 The data are not corrected for differences in rotational alignments. While it is possible to include alignment effects in the present treatment, both theory and experiment demonstrate that the influence is very slight, [81][82][83][84][85] especially at the higher energies employed in the current study. 84,85 The alignment provides a useful complementary probe, particularly for the high energy region, and is the topic of related fluorescence polarization studies.…”

“…84,85 The alignment provides a useful complementary probe, particularly for the high energy region, and is the topic of related fluorescence polarization studies. 84,85 In a simplistic view, Fig. 5 shows that the ions are becoming ''hotter'' with increasing photon energy.…”

Vibrational branching ratios in photoionization of CO and N2

“…The current study focuses on vibrational branching ratios for these systems where differences in vibrational behavior are also seen to extend far into their respective ionization continua. This study-in conjunction with previous rotational 1,2 and polarization studies 3,4 -demonstrate that molecular aspects of ionization dynamics emerge even far from threshold, and that different molecular motions probe different aspects of the photoionization process.…”

“…For example, the rotational distributions for CO were relatively flat in the lower energy region 1,2,30 ͑i.e., 20рh р50 eV) while the vibrational distributions vary significantly in this same region. Similarly, polarization data for CO 3,4 in the high energy region demonstrated that the photoelectron is ejected preferentially along the molecular axis, while the vibrational and rotational data were insensitive to this aspect of the photoelectron ejection. These observations underscore the point that measurements which emphasize molecular aspects elucidate details of the photoelectron scattering dynamics that would be otherwise inaccessible.…”

“…[1][2][3]5 The excursion in the CO vibrational branching ratio curve at h Ϸ35 eV results from the lϭ3 shape resonance in the 4 →k channel. 2,4 The higher energy regime is featureless because there is no shape resonance at higher energies, and the Cooper minima are relatively weak. 30 For N 2 , the vibrational branching ratios vary from 100 to 200 eV, while at the lower energy the results are comparatively constant.…”