Covariance-map imaging study into the fragmentation dynamics of multiply charged CF₃I formed in electron-molecule collisions

Abstract

We have previously presented a comprehensive velocity-map imaging study into the dissociative electron-ionisation dynamics of CF${}_3$I at energies ranging from 20 to 100 eV, focusing on dissociation channels of singly charged parent ions. Here we extend this work to include channels arising from doubly and triply charged CF${}_3$I ions formed in collisions with 40–100 eV electrons. Both the dication and trication can dissociate either via two-body Coulomb explosion to form CF${}_3^{+}$ + I${}^{+}$/I${}^{2+}$, or via a variety of many-body dissociation channels involving the loss of one or more neutral fluorine atoms. Covariance mapping of the charged fragments allows us to distinguish between the various possible dissociation mechanisms that could account for these products.

GRAPHICAL ABSTRACT

Keywords:

• Electron ionisation
• CF${}_3$I
• multiple ionisation
• fragmentation dynamics
• covariance-map imaging

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Acknowledgments

The authors thank Les Hill, Peter Fair, Andy Green, Howard Lambourne, Kevin Valentine, Tim Powell, John Adams, and Philip Hurst, of Oxford Chemistry's Electronics and Mechanical Workshops, for assisting us in recent upgrades to the electron-molecule crossed-beam instrument which made the present work possible.

Disclosure statement

No potential conflict of interest was reported by the authors.

Data availability statement

The data files are available on request by contacting the corresponding author.

Notes

1 In the case of CF${}_3^{+}$, the distribution is actually trimodal, but the third peak is of such low intensity relative to the first two that it appears bimodal.

Additional information

Funding

This work was supported by the EPSRC under Programme Grant EP/L005913/1 and a Doctoral Training Grant to DH, and by Lincoln College via financial support to HK.