Skip to main content
eScholarship
Open Access Publications from the University of California

Scholarly Works (5 results)

  • Article
LBL Publications (1999)
    Cover page: The Atomic and Molecular Facility on Beamline 10.0.1 at the Advanced Light Source
    • Article
    • Peer Reviewed
    LBL Publications (2000)

    High-resolution resonant Auger electron spectra of NO measured in the vicinity of the N $1s \rightarrow 2\pi$ core excitations are presented. The open shell electronic configuration of the molecule results in four excited electronic states, three of which are populated in the photoabsorption spectrum, $^2\Delta$, $^2\Sigma^-$ and $^2\Sigma^+$. Electron emission spectra obtained at different vibrational levels of the three N~;$1s$ core-excited states of NO are reported. Recently reported ab initio calculations [J. Chem. Phys. 106, 4038 (1997)] are used to generate theoretical spectra for comparison with the experimental results taking lifetime vibration interference and Auger resonant Raman effects into account. Very good agreement is found for the lowest energy $X~;^1\Sigma^+$ final ionic state. Spectra of the higher energy final ionic states are decomposed into contributions from the different $5\sigma^-12\pi^1$ and $1\pi^-12\pi^1$ configurations for comparison of the calculated and experimental partial Auger decay rates. A revised value for the adiabatic ionization energy of the $^1\Delta$ ionic state results from the deconvolution.

      Cover page: Vibrational structure and partial rates of resonant Auger decay of the N 1s -> 2pi core excitations in nitric oxide
      • Article
      • Peer Reviewed
      Chemical Sciences (2018)
      Autoionizing resonances are paradigmatic examples of two-path wave interferences between direct photoionization, which takes a few attoseconds, and ionization via quasi-bound states, which takes much longer. Time-resolving the evolution of these interferences has been a long-standing goal, achieved recently in the helium atom owing to progress in attosecond technologies. However, already for the hydrogen molecule, similar time imaging has remained beyond reach due to the complex interplay between fast nuclear and electronic motions. We show how vibrationally resolved photoelectron spectra of H2 allow one to reconstruct the associated subfemtosecond autoionization dynamics by using the ultrafast nuclear dynamics as an internal clock, thus forgoing ultrashort pulses. Our procedure should be general for autoionization dynamics in molecules containing light nuclei, which are ubiquitous in chemistry and biology.
        Cover page: Reconstruction of the time-dependent electronic wave packet arising from molecular autoionization
        • Article
        • Peer Reviewed
        UC Davis Previously Published Works (2016)
        Free-electron lasers (FEL) hold the potential to revolutionize structural biology by producing X-ray pules short enough to outrun radiation damage, thus allowing imaging of biological samples without the limitation from radiation damage. Thus, a major part of the scientific case for the first FELs was three-dimensional (3D) reconstruction of non-crystalline biological objects. In a recent publication we demonstrated the first 3D reconstruction of a biological object from an X-ray FEL using this technique. The sample was the giant Mimivirus, which is one of the largest known viruses with a diameter of 450 nm. Here we present the dataset used for this successful reconstruction. Data-analysis methods for single-particle imaging at FELs are undergoing heavy development but data collection relies on very limited time available through a highly competitive proposal process. This dataset provides experimental data to the entire community and could boost algorithm development and provide a benchmark dataset for new algorithms.
          Cover page: Single-shot diffraction data from the Mimivirus particle using an X-ray free-electron laser
          • Article
          • Peer Reviewed
          UC San Francisco Previously Published Works (2012)
          We demonstrate the use of an X-ray free electron laser synchronized with an optical pump laser to obtain X-ray diffraction snapshots from the photoactivated states of large membrane protein complexes in the form of nanocrystals flowing in a liquid jet. Light-induced changes of Photosystem I-Ferredoxin co-crystals were observed at time delays of 5 to 10 µs after excitation. The result correlates with the microsecond kinetics of electron transfer from Photosystem I to ferredoxin. The undocking process that follows the electron transfer leads to large rearrangements in the crystals that will terminally lead to the disintegration of the crystals. We describe the experimental setup and obtain the first time-resolved femtosecond serial X-ray crystallography results from an irreversible photo-chemical reaction at the Linac Coherent Light Source. This technique opens the door to time-resolved structural studies of reaction dynamics in biological systems.
            Cover page: Time-resolved protein nanocrystallography using an X-ray free-electron laser
            Top