Resonant states in cyanogen NCCN

Area of Science:

• Chemical Physics
• Quantum Chemistry
• Molecular Spectroscopy

Background:

• Transient anion states, or resonances, are crucial for understanding electron-molecule interactions.
• Cyanogen (NCCN) exhibits complex electronic structures that require detailed investigation.
• Previous models of cyanogen's electronic behavior may be oversimplified.

Purpose of the Study:

• To experimentally and theoretically identify and characterize transient anion states in cyanogen.
• To compare experimental findings with theoretical predictions for resonance positions.
• To refine theoretical models for describing electron-molecule resonances in small molecules.

Main Methods:

• Experimental electron energy loss spectroscopy to measure excitation functions for vibrationally inelastic electron scattering.
• Theoretical analysis using the regularized analytical continuation method to probe resonant states.
• Independent verification of the lowest shape resonance using the complex adsorbing potential method.

Main Results:

• Four distinct resonances were observed experimentally at 0.36 eV, 4.1 eV, 5.3 eV, and 7.3 eV.
• Theoretical calculations using analytical continuation showed good agreement for low-lying resonances but instability for higher states.
• The lowest shape resonance (2Πu) was identified and experimentally manifested as a boomerang structure.

Conclusions:

• The study successfully identified multiple transient anion resonances in cyanogen.
• Theoretical methods provide valuable insights but require further development for higher-lying states.
• The simplistic view of cyanogen as a pseudodihalogen focusing solely on the CC stretch is invalidated by these findings.