Caging of I2 in deca-dodecasil 3R: Pump–probe experiments and molecular dynamics modeling

• Published in: The Journal of chemical physics 2001-05, Vol.114 (18), p.8132-8138
• Main Authors: Ermoshin, V. A., Flachenecker, G., Materny, A., Engel, V.
• Format: Article
• Language: English
• ISSN: 0021-9606; 1089-7690
• DOI: 10.1063/1.1359739

We present transients obtained by femtosecond time-resolved spectroscopy on I2 encapsulated in well-defined cages of the crystalline microporous SiO2 modification deca-dodecasil 3R. After pump excitation into the electronic B-state, collision-induced predissociation is observed followed by recombination into A/A′ and X states, where the molecules undergo vibrational relaxation. To explain the complex time-behavior of the transient signals, molecular dynamics simulations are performed which account for the nonadiabatic transitions in I2 and the adsorbate-framework interactions. The theoretical study shows that the total signal contains contributions from four optical transitions which are influenced by predissociation and vibrational relaxation processes. A pronounced dependence of the transient signals on the probe-laser wavelength is determined by the position of the resonance window for the optical transition.