Aaron M Lindenberg

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The macroscopic characteristics of a material are determined by its elementary excitations, which dictate the response of the system to external stimuli. The spectrum of excitations is related to fluctuations in the density–density correlations and is typically measured through frequency-domain neutron1 or X-ray2–4 scattering. Time-domain measurements of(More)
The motion of atoms on interatomic potential energy surfaces is fundamental to the dynamics of liquids and solids. An accelerator-based source of femtosecond x-ray pulses allowed us to follow directly atomic displacements on an optically modified energy landscape, leading eventually to the transition from crystalline solid to disordered liquid. We show(More)
Ultrafast electron probes are powerful tools, complementary to x-ray free-electron lasers, used to study structural dynamics in material, chemical, and biological sciences. High brightness, relativistic electron beams with femtosecond pulse duration can resolve details of the dynamic processes on atomic time and length scales. SLAC National Accelerator(More)
Ultrathin semiconductors on metals constitute color filters, which selectively absorb wavelength ranges of incident light. This paper demonstrates that these coatings are attractive for tunable color devices by reversibly switching ultrathin phase-change materials on gold between two colors with femtosecond laser pulses. The optical contrast is enhanced(More)
A. M. Lindenberg,1 I. Kang,1 S. L. Johnson,1 T. Missalla,2,5 P. A. Heimann,2 Z. Chang,3 J. Larsson,4 P. H. Bucksbaum,3 H. C. Kapteyn,3 H. A. Padmore,2 R. W. Lee,5 J. S. Wark,6 and R. W. Falcone1,7 1Department of Physics, University of California, Berkeley, California 94720 2Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California(More)
The study of first-order structural transformations has been of great interest to scientists in many disciplines. Expectations from phase-transition theory are that the system fluctuates between two equilibrium structures near the transition point and that the region of transition broadens in small crystals. We report the direct observation of structural(More)
Linear-accelerator-based sources will revolutionize ultrafast x-ray science due to their unprecedented brightness and short pulse duration. However, time-resolved studies at the resolution of the x-ray pulse duration are hampered by the inability to precisely synchronize an external laser to the accelerator. At the Sub-Picosecond Pulse Source at the(More)
Intense femtosecond laser excitation can produce transient states of matter that would otherwise be inaccessible to laboratory investigation. At high excitation densities, the interatomic forces that bind solids and determine many of their properties can be substantially altered. Here, we present the detailed mapping of the carrier density-dependent(More)
We report time-resolved studies of hydrogen bonding in liquid H(2)O, in response to direct excitation of the O-H stretch mode at 3 mum, probed via soft X-ray absorption spectroscopy at the oxygen K-edge. This approach employs a newly developed nanofluidic cell for transient soft X-ray spectroscopy in the liquid phase. Distinct changes in the near-edge(More)
SLAC has two electron accelerators, the Linac Coherent Light Source (LCLS) and the Facility for Advanced Accelerator Experimental Tests (FACET), providing high-charge, high-peak-current, femtosecond electron bunches. These characteristics are ideal for generating intense broadband terahertz (THz) pulses via coherent transition radiation. For LCLS and FACET(More)