Seminars Archive

Imaging Soot and Biological Aerosols with X-ray Free Electron Lasers

Abstract
This seminar will review the single particle x-ray diffractive imaging program at the Stanford PULSE Institute for Ultrafast Energy Science. The interaction of high intensity laser light with single particles has long been a key tool in the development of aerosol science. Lasers are ideally suited to examination of particulate matter size and morphology based on scattering or chemical composition via laser desorption/ionization. Recently a new regime of laser technology was achieved at the Free electron LASer in Hamburg, FLASH, facility. This laser produces soft x-ray pulses with previously unparalleled parameters (10 fs, 7-32 nm, 1012 photons per pulse, 20 um diameter). One of the seminal FLASH experiments, single-pulse coherent lensless diffractive imaging, is most efficient when satisfying an oversampling constraint that necessitates an isolated object, i.e. individual “freestanding‿ portions of disordered matter delivered to the center of individual FEL pulses. By definition, this type of matter is an aerosol. I will discuss how aerosol science methodologies developed for single particle laser mass spectrometry were adapted to perform the first single particle imaging experiments of cells, viruses and nanoparticles at FLASH. Motivated by these exciting results, PULSE has developed a model for simulating single particle imaging of combustion-generated soot particles at X-ray FELs. This model will be used to highlight the possibilities for our high resolution single particle aerosol morphology and dynamics studies at various soft and hard x-ray FEL facilities. Finally, first results from the adaptation of aerosol methodologies to single particle imaging at the Linac Coherent Light Source, LCLS, will be briefly discussed. This research is supported through the PULSE Institute at the SLAC National Accelerator Laboratory by the US Department of Energy, Office of Basic Energy Sciences. [1] Bogan, M. J. et al. Aerosol imaging with a soft x-ray free electron laser. Aerosol Sci. Tech. 44, i-vi (2010). [2] Bogan, M. J. et al. Single particle X-ray diffractive imaging. Nano Letters 8, 310-316 (2008). [3] Benner, W. H. et al. Non-destructive characterization and alignment of aerodynamically focused particle beams using single particle charge detection. J. Aerosol Sci. 39, 917-928 (2008). [4] Bogan, M. J. et al. Aerosol sample preparation methods for X-ray diffractive imaging. J. Aerosol Sci. 38, 1119-1128 (2007). [5] Chapman, H. N. et al. Femtosecond diffractive imaging with a soft-X-ray free-electron laser. Nat. Physics 2, 839-843 (2006).