Femtosecond time-resolved electronic relaxation dynamics in tetrathiafulvalene

Area of Science:

• Physical Chemistry
• Ultrafast Spectroscopy
• Molecular Dynamics

Background:

• Tetrathiafulvalene (TTF) is a molecule of interest due to its unique electronic properties.
• Understanding its excited-state dynamics is crucial for applications in organic electronics and materials science.

Purpose of the Study:

• To investigate the ultrafast electronic relaxation dynamics of TTF initiated around 4 eV.
• To elucidate the nature of the broad double structure observed in the TTF absorption spectrum at this energy.
• To identify key relaxation pathways and intermediate states.

Main Methods:

• Femtosecond time-resolved velocity-map imaging.
• Pump-probe spectroscopy with variable wavelengths.
• Monitoring of parent cation and fragment ion transients.

Main Results:

• Detection of two distinct internal conversion processes.
• Observation of intramolecular vibrational relaxation on the femtosecond timescale.
• Assignment of a previously uncharacterized dark electronic state involved in relaxation.
• Evidence for the formation of TTF dimer.

Conclusions:

• The study reveals complex ultrafast relaxation pathways in TTF.
• A dark electronic state plays a significant role in the observed dynamics.
• Femtosecond time-resolved velocity-map imaging is a powerful tool for probing excited-state dynamics.