Resonance electron attachment to tetracyanoquinodimethane

Area of Science:

• Physical Chemistry
• Surface Science
• Materials Science

Background:

• 7,7,8,8-tetracyanoquinodimethane (TCNQ) is a molecule known for its electron-accepting properties.
• Understanding electron interactions with gas-phase molecules is crucial for various applications, including materials science and surface chemistry.

Purpose of the Study:

• To investigate the resonance interaction of low-energy electrons with gas-phase TCNQ.
• To characterize the formation and decay of TCNQ molecular negative ions.
• To explore potential mechanisms for long-lived molecular anion formation and their relevance to surface phenomena.

Main Methods:

• Dissociative electron attachment (DEA) spectroscopy was employed to study electron interactions with TCNQ.
• Density functional theory (DFT) calculations were used to determine empty orbital energies.
• Comparison with electron transmission spectroscopy (ETS) data provided further interpretation.

Main Results:

• Long-lived TCNQ molecular negative ions were detected at specific electron energies (0.3, 1.3, and 3.0 eV).
• Negative fragment formation was observed around 4 eV.
• Slow dissociative decay channels (microseconds) were identified at approximately 3 eV, with an average electron detachment time of 250 μs.
• A mechanism for the unusual formation of long-lived molecular anions above zero energy was discussed.

Conclusions:

• The study provides detailed insights into the interaction of low-energy electrons with isolated TCNQ molecules.
• The findings suggest potential electron-stimulated surface reactions on condensed TCNQ when exposed to electron beams.
• This research contributes to understanding processes in TCNQ adsorbates with excess negative charge.