Photoionisation of the H 2 molecule

The effect of vibrational autoionization on the H2+ X 2Σg+ v+ = 3, N+ state rotationally resolved photoelectron angular distributions and branching ratios has been investigated with a velocity map imaging spectrometer and synchrotron radiation. In photon excitation regions free from the influence of autoionizing Rydberg states, where direct ionization dominates, the photoelectron anisotropy parameter associated with the X 1Σg+ v″ = 0, N″ = 1 → X 2Σg+ v+ = 3, N+ = 1 transition has a value close to the theoretical maximum. However, in the vicinity of a Rydberg state, vibrational autoionization leads to a substantial reduction in anisotropy. The value of the anisotropy parameter associated with the S-branch of the photoelectron spectrum is found to be considerably higher than that predicted under the assumption that the outgoing electron can be represented solely as a p-wave. This suggests that the f-wave contribution must be taken into account to obtain a proper description of the photoionization dynamics. The observed variations in the rotationally resolved branching ratios, in the vicinity of an autoionizing resonance, depend upon the rotational level of the Rydberg state. The rotationally averaged photoelectron anisotropy parameters have been compared with the corresponding, previously calculated, theoretical results and reasonable agreement has been found. The influence of vibrational autoionization on the H2+ X 2Σg+ v+ = 0, 1, 2, 3 vibrational branching ratios has also been investigated, and the experimental results show that, in energy regions encompassing Rydberg states, these ratios deviate strongly from the Franck–Condon factors for direct ionization.

Section: Introductionsupporting

confidence: 67%

“…The possible contribution of f-waves to the description of the outgoing electron has been discussed in several theoretical studies [59][60][61][62][63][64]. Chandra [64] carried out a series of calculations to investigate the way in which various theoretical approximations affected the experimental observables.…”

Section: Photoelectron Angular Distributionsmentioning

confidence: 99%

The effect of vibrational autoionization on the H₂⁺X²Σ_g⁺state rotationally resolved photoionization dynamics

Holland¹,

Shaw²

2013

“…The absolute one-electron-capture cross sections have been measured by the initial growth-rate method in combination with the retardation technique (Tawara et al 1985). The experimental procedure and apparatus have been reported previously (Tawara et al 1985, Nakamura et a1 1994.…”

Section: Methodsmentioning

confidence: 99%

“…The charge-state distributions of scattered ions were measured in coincidence with the recoil ions. The electron-capture cross sections were measured by the initial growth-rate method (Tawara et al 1985). Absolute and i-electron-capture cross sections (aq,q-i = E, were also determined.…”

Section: Introductionmentioning

confidence: 99%

Target dependence of multi-electron processes in I^q+(q=10, 15)+rare gas (Ne, Ar, Kr and Xe) collisions

Nakamura

Currell

Danjo

et al. 1995

We have determined experimentally the absolute cross sections for i-electron capture (to projectile) and j-electron removal (from target) ( sigma q,q-ij), total electron capture ( sigma q= Sigma i sigma q,q-i), j-electron removal ( sigma qj= Sigma i sigma q,q-ij) and i-electron capture ( sigma q,q-i= Sigma j sigma q,q-ij) for the processes: Iq+(q=10 or 15)+B to I(q-i)++Bj++(j-i)e (B identical to Ne, Ar, Kr and Xe) at collision energy of 1.5q keV. Charge-state distributions of the scattered ions were measured in coincidence with the recoil ions. The absolute electron-capture cross sections were measured by the initial growth-rate method. The experimental results for sigma q and sigma qj were compared with the predictions of the extended classical over-barrier model (ECBM). The branching ratios of the multiply-excited ions produced by multi-electron transfer have also been determined.

“…Chandra [25] has studied how observables of the N = 2 branch in the description of the photoionization of H 2 are affected by the level of approximation, and, like other authors [26,27], has found them to be very sensitive to the inclusion or omission of f-wave contributions in the calculations. These calculations were only performed for He I and Ne I radiation excited photoelectrons.…”

mentioning

confidence: 96%

Synchrotron radiation excited photoelectron spectrum of with rotational resolution

Öhrwall

Baltzer²,

Bozek³

1999