Anisotropy enhanced X-ray scattering from solvated transition metal complexes

Area of Science:

• * Ultrafast structural dynamics
• * Molecular spectroscopy
• * X-ray science

Background:

• * Time-resolved X-ray scattering experiments at X-ray free-electron lasers (XFELs) often yield anisotropic signals.
• * This anisotropy originates from UV-Vis laser pulse excitation, inducing directional structural changes in molecules.
• * Analyzing these anisotropic signals is crucial for understanding ultrafast molecular processes.

Purpose of the Study:

• * To develop and demonstrate a quantitative method for analyzing anisotropic time-resolved X-ray scattering data.
• * To enhance the structural sensitivity of femtosecond X-ray scattering experiments.
• * To gain deeper insights into photoinduced structural dynamics and excitation mechanisms.

Main Methods:

• * Development of a quantitative analysis method for anisotropic scattering signals from ensembles of molecules.
• * Application of the method to time-resolved X-ray scattering data from a photoexcited solvated di-platinum complex at an XFEL.
• * Combined analysis of anisotropic and isotropic difference scattering signals.

Main Results:

• * The developed method successfully enhances structural sensitivity in time-resolved X-ray scattering.
• * Combined analysis of anisotropic and isotropic signals allows more precise determination of Pt-Pt bond length changes.
• * More information on excitation channels was obtained compared to analyzing isotropic scattering alone.

Conclusions:

• * Quantitative analysis of anisotropic scattering significantly improves the precision of structural determination in photoexcited molecules.
• * The anisotropic transient response of the solvent can be utilized to determine critical experimental parameters like the instrument response function.
• * This approach offers a more comprehensive understanding of ultrafast molecular dynamics and reaction pathways.