Chemical Dynamics with Attosecond Light Sources
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Chemical Dynamics with Attosecond Light Sources
Tue, 07/05/2024 - 11:00
Location:
Speaker:
Prof Daniel Neumark
Affiliation:
University of California, Berkeley
Synopsis:
The development of attosecond light sources in the extreme ultraviolet and soft x-ray regions of the electromagnetic spectrum has opened up new frontiers in many areas of atomic, molecular, and chemical physics, as was acknowledged in the 2023 Nobel Prize in Physics. In a collaborative effort with Steve Leone, we have used tabletop attosecond light sources to carry out a series of experiments in which ultrafast dynamics in atoms and molecules are initiated by a few-femtosecond pump pulse and transient absorption spectra are recorded using a broadband attosecond probe pulse. The energy range of our attosecond pulses has recently been extended into the soft x-ray regime. This advance enables one to probe ultrafast dynamics with elemental specificity, making use of core-to-valence transitions whose energy varies markedly across the elements. The experiments explore many phenomena including vibrational coherences in SF6 and CCl4 via impulsive stimulated Raman scattering, Jahn-Teller distortion in CH4+ triggered by strong field ionization of CH4, and “attosecond photochemistry” of allyl iodide in which soft x-ray transient absorption is used to monitor the formation and evolution of the allyl radical produced by UV photodissociation.
Biography:
Daniel M. Neumark (born 1955) is an American chemist focusing in physical chemistry and molecular structure and dynamics. He specializes in the use of ultra-high vacuum techniques (including molecular beams) and photochemistry to characterize the quantum states of elusive or short-lived chemical entities in the gas phase. Neumark obtained his B.A. and M.A. from Harvard University and went on to earn his Ph.D. in physical chemistry from University of California, Berkeley in the lab of future Nobel laureate Yuan T. Lee. From 1984 to 1986 he was a postdoctoral fellow at University of Colorado. He currently is a professor at University of California, Berkeley. He was the director of the chemical sciences division at Lawrence Berkeley National Laboratory from 2000 to 2010. Neumark won the William F. Meggers Award in 2005, the Irving Langmuir Award in 2008, the Herbert P. Broida Prize in 2013, and the Bourke Award in 2018. He is an Elected Fellow of the American Association for the Advancement of Science, American Academy of Arts and Sciences and American Physical Society.