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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Fast Beam Translational Spectroscopy


This project uses photofragment translational spectroscopy to investigate photodissociation dynamics of free radical species upon the absorption of a UV photon. The fast radical beam machine operates by producing an anionic precursor from which an electron is detached to make neutral free radicals in their ground vibrational states. These radicals are subsequently dissociated and the photofragments are collected in coincidence using a hexanode delay-line detector which records both time and position information of all photofragments produced from a given dissociating radical.

Position and arrival time of the photoproducts allows for the generation of mass, translational energy, and angular distributions. Using these respective distributions, the photofragments are identified, and the dynamics leading to their formation can be determined.

Recent Molecules Studied:

Alkyl Peroxy Radicals: t-C4H9OO, CH3OO, C2H5OO

Alkyl Perthiyl Radicals: t-C4H9SS, CH3SS

i-methylvinoxy: CH3COCH2

Project members:

Erin Sullivan

Bethan Nichols

Recent publications:

♦ "Photodissociation dynamics of the simplest alkyl peroxy radicals, CH3OO and C2H5OO, at 248 nm" E. N. Sullivan, B. Nichols, D. M. Neumark, J. Chem. Phys. 148, 033409 (2018). pdf

♦ "Investigation of the two- and three-fragment photodissociation of the tert-butyl peroxy radical at 248 nm" B. Nichols, E. N. Sullivan, M. Ryazanov, C. M. Hong, D. M. Neumark, J. Chem. Phys. 147, 134304 (2017). pdf

♦ "Photodissociation Dynamics of the i-Methylvinoxy Radical at 308, 248, and 225 nm Using Fast Beam Photofragment Translational Spectroscopy" B. Nichols, E. N. Sullivan, M. Ryazanov, D. M. Neumark, J. Phys. Chem. A 121, 579 (2017). pdf

♦ "Photodissociation dynamics of the methyl perthiyl radical at 248 and 193 nm using fast-beam photofragment translational spectroscopy" A. W. Harrison, M. Ryazanov, E. N. Sullivan, D. M. Neumark, J. Chem. Phys. 145, 024305 (2016). pdf