Introduction: Electron and Photon Initiated Chemistry

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IntroductionElectron and Photon Initiated
Chemistry

• Bill McCurdy
• Lawrence Berkeley National Laboratory

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Electron and Photon Initiated Chemistry

• Classic model of theoretical chemistry --
  Electronic structure separate from dynamics
  
• Quantum Chemistry calculation of potential
  surfaces
• Quantum or classical dynamics calculations of
  rates
• Nonclassic theoretical chemistry
• in the presence of ionizing radiation
• in electronic collisions in plasmas
• electronic structure and dynamics are inseparable

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Continuum Electronic Structure --

• At energies of low temperature plasmas the
  colliding electrons are indistinguishable from
  those of the target molecules -- electron
  correlation and dynamics are the same problem

Electron - CF4 collisions requiring 20,000
configurations per symmetry
Isaacs et al.
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One and multi-photon photoionization

• Final state is described by an electron/molecular
  ion scattering wave function.
• Coupled final channels are electronic states of
  molecular ion.
• Full coupled dynamics important for
• inner shell processes (shake-up states and
  satellites)
• resonance regions (autoionizing states)
• Valence ionization of surface adsorbed species

O2
Lucchese et al.
CO
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Electron (and Photon) Initiated Chemistry in
Extreme Environments
Applications of interest in both gas and
condensed phases and on surfaces
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Chemistry in Extreme Environments is Important to
DOE

• Plasma processing of semiconductors and other
  materials
• Etchant gases (CF4, BCL3, HBr, Cl2, ...) are
  unreactive until activated in a plasma.
• Nuclear waste, e.g., the tanks at Hanford
• cascades from decay events liberate electrons and
  ions and initiate new chemistry (inc. by electron
  attachment)
• Waste remediation -
• plasma destruction of toxics (scrubbers of flue
  gases, destruction of chemical weapons ...)

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NAS Report on Database Needs for Modeling and
Simulation of Plasma Processing -- CAMOS

• Electron collision cross section data are second
  only to data on heterogeneous processes in their
  importance to plasma processing
• The lack of fundamental data for the most
  important chemical species is the single largest
  factor limiting the successful application of
  models to problems of industrial interest

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Chaotic Evolution of a New Initiative in
Computational Science for FY 2000

• SS
• DOE Strategic Simulation Initiative becomes the
  Scientific Simulation Plan becomes SS
• Joint NSF and DOE workshop held at National
  Academy of Science (150 attendees)
• Joint NSF/DOE preliminary report emerges
  (http//rrbhpnt.asc.cise-nsf.gov/) with three
  components Science, Technology and Integration
• Presidents Information Technology Advisory
  Committee (PITAC) Report First Draft Circulated
• Emphasis on Computer Science and Technology
• Multiagency Initiative in Preparation
• Neal Lane, as head of OSTP given task to
  coordinate multiagency initiative in response to
  the PITAC report.
• DOE and NSF Response Still in Process as of
  10-9-98 !

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Scope of Original DOE Scientific Simulation
Initiative (Proposed for FY2000)

• Two Major Thrust Areas
• Climate Prediction
• Combustion Modeling
• Basic Science Component
• Materials Science
• Computational Biology
• Fusion and Plasma Physics
• Other?
• Cross Cutting Technologies
• Computer Science for Problem Solving Environments
• Computer Science for Data Management/Visualization
  
• Applied Mathematics supporting thrust areas and
  basic science
• Platforms Total Capability of 80 Tflops (peak)
  in 2003