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MES and Chemical Dynamics Beamlines Programs

Program Leader

Musahid Ahmed

Principal Investigators

Hendrik Bluhm

Mary Gilles

David Shuh

Kevin Wilson

 

Utilizing capabilities of the Chemical Dynamics Beamline and the Molecular Environmental Sciences (MES) Beamline at the LBNL’s ALS, this highly successful program employs synchrotron radiation to solve key problems in gas phase, condensed phase and interfacial chemistry that are relevant to the energy mission.

Our Chemical Mechanisms, Dynamics and Kinetics project uses tunable vacuum ultraviolet (VUV) light from the Chemical Dynamics Beamline coupled to a variety of novel instruments for probing chemical mechanisms, dynamics and kinetics of systems relevant to energy and environmental science. Molecular beam mass spectrometry in conjunction with novel reactors are used to determine the microscopic details of the mechanisms and dynamics of primary dissociation processes and elementary chemical reactions and to study the structure, energetics and chemical reactivity of highly reactive polyatomic radicals, unusual transient species, and clusters. Aerosol and heterogeneous chemistry studies are performed with state-of-the-art mass spectrometry and two dimensional chromatographic methods coupled to synchrotron radiation. The multiphase chemistry of organic particles are probed by measuring heterogeneous kinetics and product identification with isomeric specificity. Tunable synchrotron radiation combined with theoretical chemistry methods are used to probe solar system photochemistry and metal activated chemical reactions.

Figure 1 Atom to aerosol science at the chemical dynamics beamline

The MES Beamline supports our Chemical Transformations and Interfacial Science studies. Probing metal ion coordination chemistry, solvation and aqueous chemistry using molecular beams, ion trap mass spectrometers, and liquid jets coupled with electronic structure calculations and the development of novel in situ and in operando reactors comprise this project. Beamline work focuses on the molecular level investigation of interfaces under operating conditions, essential for a fundamental understanding of heterogeneous reactions at solid/vapor, solid/liquid, and liquid/vapor interfaces. The high surface sensitivity of ambient pressure X-ray photoelectron spectroscopy (APXPS) combined with tailored in situ cells, allows the correlation of the surface chemistry of a solid or liquid with other reaction parameters (e.g., yield, conversion) for a wide variety of pressing problems, such as ion segregation at liquid surfaces, the heterogeneous chemistry of fuel cell electrodes, and ultrafast charge transfer across interfaces. The scanning transmission X-ray microscope (STXM) provides spatially resolved molecular information on materials important for energy sciences and complements the APXPS investigations by expanding the probe depth and pressure range. These unique capabilities enable cutting-edge research on in operando interfacial chemistry across a wide range of areas of research, from alternative energy devices to aerosol chemistry.

Figure 2 A broad snapshot of science conducted at the molecular and environmental sciences beamline