Bowe, P. and Giammanco, F. and O'Neill, R.W. and van der Burgt, P.J.M. and Slevin, J.A.
Observation of collective effects in the multiphoton ionization of atomic deuterium.
Physical Review A, 58 (2).
The yields and time-of-flight spectra for ions produced in three-photon ionization of atomic deuterium have
been investigated as a function of laser intensity from 0.4 to 200 MW/cm2. A pulsed laser beam of 243 nm is
used, so that the photoionization is resonant with the metastable 2s state of deuterium. The production of
resonantly excited 2s atoms is measured by detecting the quenched Lyman-a radiation at time intervals both
during and after the laser pulse. The near degeneracy of the 2s-2p state manifold provides a particularly
sensitive way to monitor the presence of any electric field in the interaction volume. As the laser intensity is
increased, we observe the effects of a collective field arising from the electron-ion plasma produced by the
laser pulse. We present the results of a theoretical model where the collective motion of the ions and the
electrons is analyzed in terms of the fluid approximation. The essential features of the experimental observations
including ion yields, ion time-of-flight spectra, and metastable production versus time, are well described
by the theory.
||collective effects; multiphoton ionization; atomic deuterium;
||Science & Engineering > Experimental Physics
Dr Peter van der Burgt
||17 Aug 2010 15:36
|Journal or Publication Title:
||Physical Review A
||American Physical Society
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