Visualizing electron rearrangement in space and time during the transition from a molecule to atoms.

Authors:
Dr. Vandana Sharma, PhD
Dr. Vandana Sharma, PhD
Institute of Genetics and Hospital for Genetic Diseases
Genetics, Pharmacogenetics
Hyderabad, AP | India
Dr. Agnieszka Jaron-Becker, PhD
Dr. Agnieszka Jaron-Becker, PhD
University of Colorado at Boulder
Associate Research Professor
Boulder, CO | United States

Proc Natl Acad Sci U S A 2010 Nov 8;107(47):20219-22. Epub 2010 Nov 8.

JILA and Department of Physics, University of Colorado, Boulder, CO 80309, USA.

Imaging and controlling reactions in molecules and materials at the level of electrons is a grand challenge in science, relevant to our understanding of charge transfer processes in chemistry, physics, and biology, as well as material dynamics. Direct access to the dynamic electron density as electrons are shared or transferred between atoms in a chemical bond would greatly improve our understanding of molecular bonding and structure. Using reaction microscope techniques, we show that we can capture how the entire valence shell electron density in a molecule rearranges, from molecular-like to atomic-like, as a bond breaks. An intense ultrashort laser pulse is used to ionize a bromine molecule at different times during dissociation, and we measure the total ionization signal and the angular distribution of the ionization yield. Using this technique, we can observe density changes over a surprisingly long time and distance, allowing us to see that the electrons do not localize onto the individual Br atoms until the fragments are far apart (∼5.5 Å), in a region where the potential energy curves for the dissociation are nearly degenerate. Our observations agree well with calculations of the strong-field ionization rates of the bromine molecule.

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Source
http://dx.doi.org/10.1073/pnas.1014723107DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2996685PMC
November 2010
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