Ultrafast Electron Solvation in Room Temperature Ionic Liquid Observed by Femtosecond Time-resolved Near-IR Spectroscopy

The solvation process of electrons reflects the solvent structure and its fluctuation sensitively. The solvation process of electrons in room-temperature ionic liquid N, N, N-trimethyl-N-propylammonium bis(trifluoromethylsulfonyl) amide, N-1113(+) NTf2-, is observed with femtosecond near-IR absorption spectroscopy. A broad absorption band from the solvated electrons shows a continuous blue-shift of 0.09 eV within 1 ns of electron injection. The peak shift kinetics, well represented by a stretched exponential decay function, indicates the presence of two or more different solvation environments in this ionic liquid.