Laser-induced continuum structure in helium: ab initio non-perturbative calculations
N J Kylstra; E Paspalakis; P L Knight; N J Kylstra; Optics Section, Blackett Laboratory, Imperial College, London SW7 2BZ, UK; E Paspalakis; Optics Section, Blackett Laboratory, Imperial College, London SW7 2BZ, UK; P L Knight; Optics Section, Blackett Laboratory, Imperial College, London SW7 2BZ, UK
Журнал:
Journal of Physics B: Atomic, Molecular and Optical Physics
Дата:
1998-09-28
Аннотация:
We present the results of non-perturbative, R-matrix Floquet calculations of laser-induced continuum structures (LICS) in helium. We consider the case in which a Nd:YAG laser is used to embed the 1s4s Rydberg state in the continuum. The resulting modification of the photoionization rate of the 1s2s state is then calculated. This LICS has been studied recently by Halfmann et al (1998 Phys. Rev. A 58 R46) and good agreement with their experimental and theoretical findings is obtained. We also investigate the effects of incoherent channels due to higher-order multiphoton processes and LICS involving the 1s4d state. The validity of the simple two-level models that are frequently used for modelling LICS is tested by comparing these results with R-matrix Floquet calculations.
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