The Neumark Group
Department of Chemistry, University of California Berkeley
and Chemical Science Division, Lawrence Berkeley National Laboratory
Slow photoelectron velocity-map imaging spectroscopy
Fast beam translational spectroscopy
Femtosecond Time-resolved photoelectron imaging
Molecular beam reactive scattering and photodissociation
Spectroscopy and dynamics in helium droplets
Spectroscopy and dynamics in liquid microjets
Spectroscopy and Dynamics in Liquid Microjets
Femtosecond time-resolved photoelectron spectroscopy (TRPES) on liquid microjets is used to study the ultrafast dynamics of species of interest in high vapor pressure solvents. By monitoring the time evolving kinetic energy of the detached electron, we are able to record decay lifetimes, solvation timescales, and binding energies of a wide variety of solutes.
We have used this technique to study the solvation and excited state relaxation dynamics of solvated electrons in water and other solvents. Solvated electrons are a fundamental species in the condensed phase; as the simplest quantum solutes, they serve as the benchmark for our understanding of basic solute-solvent phenomena. Furthermore, when formed by ionizing radiation they are highly reactive and can lead to DNA damage.
Our current focus is on the photophysics of DNA and increasing our understanding of the process by which low energy electrons can cause genetic damage through electron attachment. Many of these states are difficult to observe through traditional Ti:Sapph femtosecond laser techniques because their binding energies are in excess of 6eV. To this end, a new setup is being developed to generate a high harmonic probe.
Nucleobases, nucleosides, nucleotides
♦ "Isotope effect on hydrated electron relaxation dynamics studied with time-resolved liquid jet photoelectron spectroscopy" M. H. Elkins, H. L. Williams, D. M. Neumark, J. Chem. Phys. 144, 184503 (2016). pdf
♦ "Dynamics of electron solvation in methanol: Excited state relaxation and generation by charge-transfer-to-solvent" M. H. Elkins, H. L. Williams, D. M. Neumark, J. Chem. Phys. 142, 234501 (2015). pdf
♦ "Relaxation mechanism of the hydrated electron" M. H. Elkins, H. L. Williams, A. T. Shreve, D. M. Neumark, Science 342, 1496 (2013). pdf