| Budget Amount *help |
¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 2003: ¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 2002: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Research Abstract |
Two major results were achieved during the duration of research. These include,
(1) Photoion measurements of helium two electron photoexcitation in a strong electric field.
(2) The achievement of "Lifetime Resolved Fluorescence Spectroscopy"
The former (1) concerns multielectron photoexcitation of atoms in a strong static electric field. The project has opened virgin territory for new research on atomic structure and dynamics in a situation where the effect of electron correlation is comparable to that of the external electric field. As a matter of fact parallel developments in theory has been quick to come by, including the work on propensity rules of perturbations (Tong & Lin, Phys. Rev. Lett. 92, 223003, 2004). The implicati9ns to solid state physics, such as the behaviour of quasi-free electrons in electric fields also merit further exploration. An apparatus capable of imposing an electric field exceeding 100kV/cm has been constructed, tested at the Photon Factory, and the final measu
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rements were made at the Advanced Light Source at Berkeley, taking advantage of the high resolution and high flux available at third generation synchrotron light sources.
The latter (2) result came as a new development. The strong field apparatus was originally designed only to accommodate photoion detection. Nevertheless, based mainly on the initiative of our postdoctoral fellow James Harries, implementations were made to accomplishi the detection of fluorescence and metastable atoms. This employs single-bunch operation of the synchrotron ring and makes use of the time structure of the signals to to separately detect fluorescence and meta-stable species. It was found particularly useful that the accurate determination of radiative lifetime became possible. This enabled the measurement of the two dimensional spectrum of excitation energy versus radiative lifetime "profile". The few to several lifetimes corresponding to different final ionic states can be analyzed from the 2D spectrum. This amounts to achieving the measurement of photon energy scan spectrum with constant final ionic state (Lifetime Resolved Fluorescence Spectroscopy). It is our claim that this is the third new method, with new merits and demerits in comparison to constant ionic state (CIS) electron spectroscopy, or energy analysis of fluorescence. Less
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