The successful installation of the Advanced Light Source's (ALS's) second elliptically polarizing undulator (EPU) in Sector 11 of the storage ring during the April shutdown marked an important milestone in the construction of a major new ALS facility: a beamline dedicated to molecular environmental science (MES). MES research focuses on molecular-scale understanding of environmentally important species--their chemical and physical forms, spatial distribution, and reactivity in natural and man-made materials--as well as the processes (chemical and biological) that affect their stability, transformations, mobility, and toxicity. It is an interdisciplinary field involving complex interactions that make high-intensity, tunable synchrotron light an indispensable research tool. The high brightness and flux of the new beamline will allow unparalleled spatial and spectral resolution. A significant fraction of experiments being performed at existing, oversubscribed beamlines at the ALS are MES-related and will benefit from an MES-optimized and dedicated beamline. The project is on track to be completed on schedule and at budget this fall.
Beamline 11.0.2 will produce synchrotron radiation from 75 to 2000 eV with a flux of 1012 photons/s. The beamline will include a wet spectroscopy endstation (beam size at focal point: 7 x 50 micrometers) and a high-pressure photoelectron spectroscopy endstation; in addition, a scanning transmission x-ray microscope (STXM) will be transferred from Beamline 7.0.1. The research program will exploit the unique capabilities of the endstations coupled to the specialized optical design of the beamline. Its "wet" capabilities will help provide a bridge from model systems to the real world. The spectroscopic tools available in the surface-science-style endstations include microbeam near-edge x-ray absorption fine structure (NEXAFS), photoelectron spectroscopy (PES), and several methodologies that fall under x-ray emission spectroscopy (XES). Examples of initial studies include the investigation of water, small molecules, and metal ions at representative interfaces. Other planned experiments will explore catalysis under realistic pressure conditions, the nature of liquid surfaces, and the interactions of metal ions with small, mineralogically important particles.
David Shuh (Chemical Sciences Division) is the MES beamline project leader, Tony Warwick is the project manager, Jim Comins is the lead engineer, Steve Marks is the insertion device engineer, and Tolek Tyliszczak is the beamline scientist. Members of the MES research team include Miquel Salmeron (Materials Sciences Division), Glenn Waychunas (Earth Sciences Division), Anders Nilsson (University of Stockholm and Stanford University), Gordon Brown, Jr. (Stanford University), Satish Myneni (Princeton University), Scott Chambers (Pacific Northwest National Laboratory), Sam Traina (Ohio State University), Brian Tonner (University of Central Florida), Lou Terminello (Lawrence Livermore National Laboratory), David Clark (Los Alamos National Laboratory), and John Gland (University of Michigan). The MES project is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences, and Division of Materials Sciences.