Ultrafast X-ray diffraction of photodissociation of iodoform in solution

Abstract

We studied structural dynamics in the photodissociation of iodoform (CHI3) dissolved in methanol by time-resolved x-ray diffraction. A femtosecond laser pulse induces the bond-breaking of an iodine atom from iodoform and an x-ray pulse generated from a synchrotron gives time-dependent diffraction signal which contains the structural information of photoproducts with 100 ps time-resolution and 0.001 Å spatial resolution. CHI 2 radical and I atom are formed by the results of the ultrafast photodissociation of iodoform and these intermediates recombine to form iodoform again via geminate recombination. The iodine atoms which escape from the cages nongeminately recombine to form I2. Solvent dynamics, heating and solvent expansion, caused by photodissociation, are also explained from time-resolved x-ray diffraction data. © 2007 American Institute of Physics.