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 photodissociation dynamics

Spectroscopy and dynamics in helium droplets

Attosecond spectroscopy

Spectroscopy and dynamics in liquid microjets

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Spectroscopy and Dynamics in Liquid Microjets

Synopsis:

Femtosecond time-resolved photoelectron spectroscopy on liquid microjets (LPES) is used to study the ultrafast dynamics of solutes in high vapor pressure solvents. By monitoring the time-evolving kinetic energy of the detached electron, we are able to record transient lifetimes, solvation timescales, and binding energies of a wide variety of species.


Our current focus is on the photophysics of DNA, In particular, we are interested in providing a molecular-scale understanding of the process by which low energy electrons can cause genetic damage. It is widely accepted that these electrons attach to DNA components to form a transient molecular anion; however, this species has never been observed experimentally.


Many of these states are difficult to observe through traditional femtosecond laser techniques because their binding energies are in excess of 6 eV. To this end, a new setup is currently being built to generate a high harmonic femtosecond probe pulse to be used in LPES experiments. We will employ a semi-infinite gas cell to generate harmonics across a broad energy regime. Stay tuned!

Molecules studied:

Nucleobases, nucleosides, nucleotides

Solvated electrons

Project members:

Holly Williams

Blake Erickson

Zachary Heim

Erica Liu

Recent publications:

♦ "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

♦ "Photoelectron spectroscopy of solvated electrons in alcohol and acetonitrile microjects" A. T. Shreve, M. H. Elkins, D. M. Neumark, Chem. Sci. 4, 1633 (2013). pdf