Contrasting Dynamics in Isoelectronic Anions Formed by Electron Attachment.

Area of Science:

• Physical Chemistry
• Chemical Physics
• Molecular Dynamics

Background:

• Cyanogen (NCCN) and cyanoacetylene (HCCCN) are isoelectronic molecules with similar properties.
• Dissociative electron attachment (DEA) is a key process for studying molecular bond cleavage.

Purpose of the Study:

• To investigate and compare the dissociation dynamics of NCCN and HCCCN induced by DEA.
• To understand the factors contributing to the different fragmentation pathways observed in these isoelectronic molecules.

Main Methods:

• Velocity map imaging (VMI) was used to analyze the CN- fragment produced from DEA.
• Electron energy loss (EEL) spectra were employed to identify parent resonance states.

Main Results:

• Both NCCN and HCCCN produce CN- with similar energy dependence via resonant electron attachment.
• VMI revealed significant differences in excess energy partitioning and fragment angular distributions between the two molecules.
• The observed differences were attributed to nuclear frame distortion during resonance formation in HCCCN.

Conclusions:

• The study elucidates distinct dissociation dynamics in isoelectronic NCCN and HCCCN following DEA.
• A mechanism involving nuclear frame distortion in HCCCN explains the observed dynamic differences and the CN- cross-section magnitude discrepancy.
• This research provides insights into electron-molecule interactions and fragmentation pathways.