MES and Chemical Dynamics Beamlines
Molecular Environmental Sciences (MES) Beamline 11.0.2 Facility
The Advanced Light Source-Molecular Environmental Sciences (MES) Beamline 11.0.2 Facility at Lawrence Berkeley National Laboratory (LBNL) is a national user facility for soft X-ray synchrotron radiation which was established in late 2002. The beamline conforms to the U.S. Department of Energy (DOE) Office of Basic Energy Sciences (BES) general user facility model. The MES Beamline is managed and supported by the Chemical Sciences Division (CSD) of LBNL in partnership with the ALS. The MES Beamline serves two branchlines (spectroscopy 18.104.22.168 and microscopy 22.214.171.124) and two facility endstations that share beamtime from a 5-cm-period elliptical polarization undulator (EPU) providing soft X-ray photons from ~75 eV to 2000 eV. The primary endstation on the spectroscopy branchline is the ambient pressure photoelectron spectrometer (APPES) system used for surface science investigations at pressures up to 10 Torr. In addition, a second endstation (APPES-II) is used as a platform for several different experimental chambers, among them a droplet train instrument for the investigation of liquid/vapor interfaces and a microscopy chamber for the development of 100 nm resolution, zone plate-based ambient pressure photoemission microscopy (APSPEM). The scanning transmission X-ray microscope (STXM) endstation on the microscopy branchline has spectromicroscopy capabilities of 9 nm spatial resolution (at present the best resolution of all X-ray microscopes) and spectral E/∆E of greater than 8500. All MES endstations are currently world-leading, best-in-class instruments.
The scientific themes at the MES Beamline center around spatially-resolved and spectroscopic investigations of materials using soft X-ray techniques under realistic controlled environments of pressure and temperature. They include ambient pressure surface studies of solid/vapor and liquid/vapor interfaces using in situ techniques. Scientific areas of investigation are: heterogeneous chemical reactions at solid and liquid interfaces; nanoscience (including nano-biogeochemistry); energy science (fuel cells, solar cell materials); aerosol and atmospheric science; heterogeneous catalysis; magnetization dynamics; actinide science; environmental science; atomic molecular and optical science.
A,B Small- and large-scale STM images of FeOx/Pt(111) films after 20 Torr CO at 520 K. C APPES
measurements of a FeOx/Pt(111) film during exposure to 1 Torr CO at room temperature
(lower spectra) and 510 K (upper spectra). The inset depicts the proposed Fe3O2 structure with Pt
atoms in the hollow sites. (Pt: gray, Fe: pink, O: red).
Research Center Leader
Chemical Dynamics Beamline
The Chemical Dynamics Beamline at the Advanced Light Source (ALS), designated beamline 9.0.2, is a user facility dedicated to state-of-the-art investigations in combustion dynamics, aerosol chemistry, imaging mass spectrometry, biomolecule energetics, spectroscopy, kinetics, and state-resolved chemical dynamics processes using tunable vacuum ultraviolet light for excitation or detection. The broad goals of the Chemical Dynamics Beamline are to perform high quality investigations in chemical physics and dynamics, while providing the user community with efficient access to the synchrotron and its sophisticated equipment, in order to fulfill the missions and interests of the Department of Energy (DOE). The Chemical Dynamics Beamline is open to all potential users through the general user proposal process administered by the ALS.
Research Center Leader
Chemical Dynamics Beamline Facility
The primary purpose of this program is to support studies in chemical physics and dynamics at the Advanced Light Source (ALS), by providing state-of-the-art experimental resources for staff and visiting scientists to undertake studies of fundamental chemical processes. Key scientific problems addressed at the beamline include:
- The microscopic details of the mechanisms and dynamics of primary dissociation processes and elementary chemical reactions.
- The properties and decay dynamics of molecules in highly excited, transient, or metastable states.
- The structure, energetics and chemical reactivity of polyatomic radicals, unusual transient species, droplets, aerosols, biomolecules, and clusters.
- New spectroscopic and dynamical tools such as imaging detection of photoelectrons, 2 color pump-probe spectroscopies and pulsed field, and Rydberg ionization techniques. (Note, there are several kinds of imaging described in this document – spatial imaging of surface materials by mass spectral detection of desorbed molecules, photoelectron and photoion angular imaging which derives photoelectron or photoion momentum and angular distributions, and 3-dimesional time-resolved "imaging" of reaction products (mass, time, and photon energy) in gas kinetics experiments, all of which are referred to as imaging).
- Investigation of chemically complex macroscopic systems such as flame dynamics, laser ablation, and reaction kinetics in order to develop more precise models of realistic combustion systems.
- Performing chemical imaging on the nanoscale to elucidate the spatial location of complex organic molecules on surfaces with relevance to combustion chemistry, atmospheric sciences and biological systems