Photodissociation dynamics of the iodide-uracil (I−U) complex
Abstract
Photofragment action spectroscopy and femtosecond time-resolved photoelectron imaging are utilized to probe the dissociation channels in iodide-uracil (I− ⋅ U) binary clusters upon photoexcitation. The photofragment action spectra show strong I− and weak [U—H]− ion signal upon photoexcitation. The action spectra show two bands for I− and [U—H]− production peaking around 4.0 and 4.8 eV. Time-resolved experiments measured the rate of I− production resulting from excitation of the two bands. At 4.03 eV and 4.72 eV, the photoelectron signal from I− exhibits rise times of 86 ± 7 ps and 36 ± 3 ps, respectively. Electronic structure calculations indicate that the lower energy band, which encompasses the vertical detachment energy (4.11 eV) of I−U, corresponds to excitation of a dipole-bound state of the complex, while the higher energy band is primarily a π–π∗ excitation on the uracil moiety. Although the nature of the two excited states is very different, the long lifetimes for I− production suggest that this channel results from internal conversion to the I− ⋅ U ground state followed by evaporation of I−. This hypothesis was tested by comparing the dissociation rates to Rice-Ramsperger-Kassel-Marcus calculations.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Jul 28, 2016
- Source ID
- 10.1063/1.4959858
Entities
People
- Alice Kunin
- Caroline E. H. Dessent
- Daniel Neumark
- Edward Matthews
- Naruo Yoshikawa
- Wei-Li Li
Organizations
- Air Force Office of Scientific Research
- European Research Council
- Lawrence Berkeley National Laboratory
- National Science Foundation
- Science and Technology Facilities Council
- University of California
- University of York