Department of Chemistry

Current Group Research

Ultrafast Intersystem Crossing Dynamics

Our research group investigate molecules that challenge conventional paradigms in photochemistry. One of such traditional views is that the rate of internal conversion (IC) is always larger than that of intersystem crossing (ISC). However, molecules can exhibit excited-state non-equilibrium dynamics when their singlet and triplet states are strongly coupled by spin-orbit interactions; the so-called strongly non-adiabatic regime. In these molecules, the distinction between singlet and triplet states is no longer well-defined and understanding their excited-state dynamics requires the use of ultrafast time-resolved techniques, high-level ab initio calculations, and mixed quantum-classical dynamics methods that model non-adiabatic and spin-orbit couplings on equal footing. Developing and refining a quantitative understanding of the excited-state dynamics in these molecules, has the potential to change comtemporary views on how we think about the photochemistry and excited-state dynamics in these molecules.

Non-Equilibrium Dynamics


Recent Publications

  • Brister, M.; Crespo-Hernández, C. E. "Direct Observation of Triplet-State Population Dynamics in the RNA Uracil Derivative 1-Cyclohexyluracil", J. Phys. Chem. Lett. 2015, 6, 4404-4409. Access article
  • Pollum, M.; Martínez-Fernández, L.; Crespo-Hernández, C. E.; "Photochemistry of Nucleic Acid Bases and their Thio- and Aza-Analogues in Solution", Top. Curr. Chem. 2015, 355, 245-327. Invited Review Chapter. Access article
  • Pollum, M.; Jockusch, S.; Crespo-Hernández, C. E. "Increase in the Phooreactivity of Uracil Derivatives by Doubling Thionation", Phys. Chem. Chem. Phys. 2015, 17, 27851-27861. Access article
  • Pollum, M.; Jockusch, S.; Crespo-Hernández, C. E.; "2,4-Dithiothymine as a Potent UVA Chemotherapeutic Agent", J. Am. Chem. Soc. 2014, 136, 17930-17933. Access article
  • Pollum, M.; Crespo-Hernández, C. E.; "Communication: The dark singlet state as a doorway state in the ultrafast and efficient intersystem crossing dynamics in 2-thiothymine and 2-thiouracil", J. Chem. Phys. 2014, 140, 071101. Access article
  • Vogt, R. A.; Reichardt, C.; Crespo-Hernández, C. E.; "Excited-State Dynamics in Nitro-Naphthalene Derivatives: Intersystem Crossing to the Triplet Manifold in Hundreds of Femtoseconds", J. Phys. Chem. A 2013, 117, 6580-6588. Access article
  • Vogt, R. A.; Gray, T. G.; Crespo-Hernández, C. E.;"Subpicosecond Intersystem Crossing in Mono- and Di-(Organophosphine)gold(I) Naphthalene Derivatives in Solution", J. Am. Chem. Soc. 2012, 134, 14808–14817.Access article
  • Reichardt, C.; Guo, C.; Crespo-Hernández, C. E.;"Excited-State Dynamics in 6-Thioguanosine from the Femtosecond to Microsecond Time Scale", J. Phys. Chem. B 2011, 115, 3263-3270.Access article
  • Reichardt, C.; Crespo-Hernández, C. E.; "Room-Temperature Phosphorescence of the DNA Monomer Analogue 4-Thiothymidine in Aqueous Solutions after UVA Excitation", J. Phys. Chem. Lett. 2010, 1, 2239-2243.Access article
  • Reichardt, C.; Crespo-Hernández, C. E.; "Ultrafast Spin Crossover in 4-Thiothymidine in an Ionic Liquid", Chem. Comm. 2010, 46, 5963-5965.Access article
  • Reichardt, C.; Vogt, R. A.; Crespo-Hernández, C. E.; "On the Origin of Ultrafast Nonradiative Transitions in Nitro-PAHs: Excited-State Dynamics in 1-Nitronaphthalene", J. Chem. Phys. 2009, 131, 224518.Access article