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Atomic, Molecular and Optical Science Instrument
The AMO instrument is situated on one of the soft x-ray branches of the LCLS that delivers intense ultra short pulses of x-rays from the FEL. Instrumentation is designed to minimize losses and deliver the maximum possible x-ray intensity to the interaction region. Gaseous targets of atoms, molecules, clusters, or nanoscale objects such as protein crystals or viruses are typically used in the AMO instrument with electron and ion spectrometers as well as large area detectors for x-ray diffraction measurements. Science performed with the AMO instrumentation includes fundamental studies of light-matter interactions in the extreme x-ray intensity of the LCLS FEL beam, time-resolved photoionization, x-ray diffraction of nanocrystals and single shot imaging of non-reproducible objects.
The interaction of ionizing radiation with matter has been a topic of much study since Hertz observed (1887) and Einstein described (1905) the photoelectric effect. While the mechanisms of excitation and ionization following the illumination of a sample with a weak beam of X-rays are well understood, little is known about the processes which occur when an intense beam of X-ray radiation strikes a target. Novel multi-electron processes are expected to occur and states of matter never before seen created. The goal of the AMO instrument is to study the interaction of the intense, short pulses of X-rays from the LCLS with the simplest forms of matter; atoms, molecules and clusters, to expand the understanding of which processes are important at different intensity regimes.
The extremely short pulses of X-rays from the LCLS provide a unique capability to study chemical processes at their natural time-scale. X-rays, such as those produced by the LCLS, interact with electrons in matter, exciting or ionizing them or scattering from them. Electron dynamics occur on the attosecond time-scale, much faster than the duration of the LCLS pulse. Nuclear dynamics (the motion of nuclei in a molecule) occur on the femtosecond time scales, however, a time scale that the LCLS is ideally suited to study, and the electronic structure of a molecule adjusts to the changing nuclear structure. Furthermore, photoionization of inner-shell electrons provide a site-specific probe of the electronic structure of a molecule, i.e. allowing electrons from a carbon atom to be differentiated from those of an oxygen atom. The LCLS is therefore a powerful tool for studying the motion of atoms in molecules reactions initiated by an external trigger (i.e., laser).
Near Experimental Hall, Hutch 1 » complete instrument map
SLAC National Accelerator Laboratory, Menlo Park, CA
Operated by Stanford University for the U.S. Dept. of Energy