Nonadiabatic Dynamics Studied by Liquid-Jet Time-Resolved Photoelectron Spectroscopy

Area of Science:

• Physical Chemistry
• Spectroscopy
• Materials Science

Background:

• High vapor pressure liquids and solutions were previously difficult to study using vacuum-based methods.
• Liquid microjet techniques combined with photoelectron spectroscopy (PES) enable high-vacuum investigations of these systems.
• Time-resolved PES (TRPES) offers state-specific insights into ultrafast dynamics.

Purpose of the Study:

• To review recent progress in understanding solvation and excited state dynamics of the solvated electron and nucleic acid constituents (NACs) using liquid microjet PES and TRPES.
• To highlight the capabilities of these techniques for probing electronic properties and relaxation pathways.
• To discuss future prospects for advanced studies with new light sources.

Main Methods:

• Liquid microjet photoelectron spectroscopy (PES) for probing electronic properties.
• Time-resolved PES (TRPES) for investigating ultrafast excited state dynamics.
• Ultraviolet (UV) pump-UV probe spectroscopy and advanced light sources (extreme UV, soft X-ray).

Main Results:

• Accurate binding energies for the solvated electron in various high vapor pressure solvents were measured.
• Femtosecond TRPES revealed a 75 ± 20 fs lifetime for solvated electron relaxation in water, supporting a non-adiabatic mechanism.
• TRPES studies on NACs identified distinct relaxation lifetimes and elucidated the absence of the ¹nπ* state signal in thymine derivatives, with conformational differences influencing excited state lifetimes in thymidine monophosphate.

Conclusions:

• Liquid microjet PES and TRPES are powerful tools for elucidating the electronic properties and dynamics of challenging liquid systems.
• These techniques provide crucial state-specific information on the solvated electron and NACs.
• Future advancements with novel light sources will enable more comprehensive studies, including core-level spectroscopy.