FIG. 7.

Schematic of (a) our experimental approach using TRXSS experiment and (b) data analysis. Upon irradiation at 400 nm, I₃^– ion dissociates into I₂^– and I, and the temperature of the solution increases. By taking the difference between scattering patterns measured before and 100 ps after laser excitation, only the laser-induced changes are extracted with all other background contributions being eliminated. The structural information can be extracted by the maximum likelihood estimation using five fitting parameters. Three bond distances of I₃^– can be clearly identified, giving the exact structure of I₃^– ion in various solvents.