Time-resolved photoion imaging spectroscopy: Determining energy distribution in multiphoton absorption experiments

Area of Science:

• Physical Chemistry
• Atomic and Molecular Physics
• Chemical Physics

Background:

• Multiphoton absorption is crucial for understanding molecular excitation.
• Determining excitation energy distribution and photon absorption cross sections is challenging.

Purpose of the Study:

• To present a novel approach for quantifying excitation energy distribution from multiphoton absorption.
• To establish a method for determining absolute photon absorption cross sections.

Main Methods:

• Utilized time-resolved photoion velocity map imaging spectrometry with a low-fluence, unfocused laser.
• Employed a cascade decay model to link energy distribution with ion species detection probability.
• Solved a Poisson's equation to extract the energy distribution variable.

Main Results:

• Successfully determined the excitation energy distribution for C60 molecules.
• Validated the approach by comparing experimental data with simulations.
• Established a direct link between ion species yield and energy distribution.

Conclusions:

• The proposed method accurately determines excitation energy distribution and absolute photon absorption cross sections.
• This technique is applicable to a broad range of molecules and clusters with similar decay mechanisms.
• Offers a pathway for detailed characterization of molecular photoexcitation processes.