Molecular Photodynamics in Superfluid He

Abstract

A fruitful investigation of photodynamics in superfluid helium was accomplished under this AFOSR grant. The author carried out the first real-time measurements of molecular dynamics in superfluid helium, and he introduced the first method for simulations of dynamics (all other methods aim at calculating stationary eigenstates). Moreover, he addressed the principal question that he had set out to investigate, namely, the scaling of concepts of superfluidity to molecular length and time scales. This was accomplished by the combination of ultrafast time-resolved measurements, high-level ab initio theory to develop effective potentials, and the development of time-dependent density functionals to simulate the observables and to test out the predictions of two-fluid hydrodynamics that was originally developed to treat macroscopic phenomenology in superfluid helium. In the first of the publications in this field, the author demonstrated the use of strong-fields in superfluid helium to generate Rydberg states that lie above 18 eV. The experiments allowed the detailed description of strong-field induced ionization, localization of charges, formation of electron bubbles, and their diffusion-controlled recombination. With a nonparametric theory, he was able to reproduce all observables - photocurrent, ion yield, laser-induced fluorescence as a function of intensity and time - to develop one of the most complete descriptions of strong-field ionization and dielectric breakdown in the condensed phase. An important follow-up to this work was to demonstrate the contrast between He and Xe by carrying out strong-field ionization experiments in liquid Xe. With the method for sudden generation of Rydberg states developed, he carried out time-dependent measurements of the liquid response to Rydberg excitations.

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Document Details

Document Type
Technical Report
Publication Date
Jan 01, 2004
Accession Number
ADA425950

Entities

People

  • V. A. Apkarian

Organizations

  • University of California, Irvine

Tags

Communities of Interest

  • Energy and Power Technologies

DTIC Thesaurus Topics

  • Chemistry
  • Computational Chemistry
  • Dynamics
  • Electrons
  • Femtosecond Lasers
  • Ground State
  • Hot Wire
  • Hydrodynamics
  • Ionization
  • Laser Induced Fluorescence
  • Laser Spectroscopy
  • Lasers
  • Low Temperature
  • Measurement
  • Molecular Dynamics
  • Simulations
  • Spectroscopy

Fields of Study

  • Physics

Readers

  • Optical Physics and Photonics.
  • Plasma Physics.
  • Quantum spin resonance or Electron Paramagnetic Resonance spectroscopy.

Technology Areas

  • Directed Energy
  • Microelectronics
  • Microelectronics - Graphene