^{1,a)}, D. Céolin

^{1}, M. Gisselbrecht

^{1}and S. L. Sorensen

^{1}

### Abstract

The angular anisotropy for selected dissociation channels is measured at resonantly excited states of and symmetries at the C and O K-shell ionization edges of carbonyl sulfide. While the kinetic energy released in the reaction is mainly independent of the excitation energy, the angular anisotropy and momentum correlation clearly show deformation of the OCS molecule in the C state. The discovery of a two-body fragmentation channel with a well defined angular anisotropy indicates the rapid formation of the CSO isomeric species.

We gratefully acknowledge assistance from the MAX-laboratory staff, in particular to Maxim Tchaplyguine. Funding for this work was granted from the Knut and Alice Wallenberg foundation and the Swedish Research Council (VR).

I. INTRODUCTION

II. EXPERIMENT

III. RESULTS AND DISCUSSION

A. Angular anisotropy of fragments

B. Dissociation of the triply ionized molecule

C. Fragment correlation

D. Isomerization

IV. CONCLUSION

## Figures

(a) A schematic diagram of the geometry of the setup. (b) Two-dimensional histogram representing the detector area showing fragments from nitrogen dissociation at the N state. The plot shows the number of ions which arrive in coincidence with ions at each detector coordinate. (c) The angular distribution of all fragments from the pathway , from which the -parameter has been estimated. The calculated distribution for is shown with a solid line.

(a) A schematic diagram of the geometry of the setup. (b) Two-dimensional histogram representing the detector area showing fragments from nitrogen dissociation at the N state. The plot shows the number of ions which arrive in coincidence with ions at each detector coordinate. (c) The angular distribution of all fragments from the pathway , from which the -parameter has been estimated. The calculated distribution for is shown with a solid line.

Histogram of fragments from the dissociation channel for resonant and nonresonant cases. (a) Distribution of fragments at C (288.08 eV). (b) Distribution of fragments measured at 285 eV. The direction of the polarization vector is shown. The distribution of fragments is plotted as a function of the angle (see Fig. 1) after integration of Eq. (3) for (c) C and (d) off resonance.

Histogram of fragments from the dissociation channel for resonant and nonresonant cases. (a) Distribution of fragments at C (288.08 eV). (b) Distribution of fragments measured at 285 eV. The direction of the polarization vector is shown. The distribution of fragments is plotted as a function of the angle (see Fig. 1) after integration of Eq. (3) for (c) C and (d) off resonance.

The KER distribution of each fragment and the total kinetic energy. (a) C compared to C (b) C compared to off resonance. The ratios of fragment energies presented in a Dalitz plot (c) C and (d) C .

The KER distribution of each fragment and the total kinetic energy. (a) C compared to C (b) C compared to off resonance. The ratios of fragment energies presented in a Dalitz plot (c) C and (d) C .

Angular correlations between fragments from complete dissociation to atomic fragments. Each plot contains the data for excitation to the C state, the C state and the off resonance measurement. (a) Histogram as a function of angle for the triple ionization events. (b) Histogram as a function of angle for the three-body double ionization events. is defined as the angle between the vectors and .

Angular correlations between fragments from complete dissociation to atomic fragments. Each plot contains the data for excitation to the C state, the C state and the off resonance measurement. (a) Histogram as a function of angle for the triple ionization events. (b) Histogram as a function of angle for the three-body double ionization events. is defined as the angle between the vectors and .

A histogram of the intensity as a function of bond angle for the two Renner–Teller components at the C state. The events corresponding to the bent geometry and the linear geometry are compared.

A histogram of the intensity as a function of bond angle for the two Renner–Teller components at the C state. The events corresponding to the bent geometry and the linear geometry are compared.

Comparison of angular correlations from the three-body breakup of for O and O states.

Comparison of angular correlations from the three-body breakup of for O and O states.

The channel was found at the C state. This channel arises as a consequence of isomerization of the dication. (a) The KER distribution. (b) The angular distribution of fragments and a fit to the parameter. The positive anisotropy implies that the bending motion cannot be separated from the core-excitation.

The channel was found at the C state. This channel arises as a consequence of isomerization of the dication. (a) The KER distribution. (b) The angular distribution of fragments and a fit to the parameter. The positive anisotropy implies that the bending motion cannot be separated from the core-excitation.

## Tables

Angular asymmetry parameters for dissociation channels at the C 1s and O 1s ionization edges. The estimated error in these values is .

Angular asymmetry parameters for dissociation channels at the C 1s and O 1s ionization edges. The estimated error in these values is .

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