Ultrafast electron diffraction: determination of radical structure with picosecond time resolution

Using ultrafast electron diffraction (UED) with the temporal diffraction-difference method recently developed in this laboratory, we report accurate determination of the radical (CF2) structure in the dissociation of diiododifluoromethane (CF2I2) with picosecond time resolution. Time-zero was clocked accurately within 2 ps and both iodine atoms were found to be liberated in less than 4 ps. The structure, absolute fraction, and electronic state of the radical were determined. The CF2 radical was found to be in X1A1 ground state with C–F and F⋯F distances of 1.30(±0.02) Å and 2.06(±0.06) Å, respectively.