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In the present project, the multiphoton excitation and ionization of rare gases and several nonlinear processes under excitation by different laser beams are studied. The main goal of the project is explanation of several anomalies in laser-matter interaction known for more than two decades, but which have remained unexplained so far. The basic idea is that all these anomalies result from laser-induced modification of atomic continuum when the dressing of a continuum by laser field and bound atomic states leads to formation of the so-called laser-induced continuum structures and it modifies significantly the excitation and ionization processes. These “anomalous” ionization processes are especially well pronounced with nongaussian light beams, where the amplitude and phase profiles differ significantly from the well-known Gaussian beams. Thus, such novel and nontraditional laser beams will serve as an effective tool in study of these specific effects of laser-matter interaction. Several novel types of laser beams and beam combinations (Bessel beams, segmented conical or Mathieu beams, crossed laser beams, and others) will be used, whereas the ordinary Gaussian beams will serve as reference ones. It is expected that a standard interpretation of experiments on multiphoton excitation and ionization should be modified essentially because of possible laser-induced structuring of the ionization continuum. Besides, experimental and theoretical study with novel types of beams will give additional information about several interesting and potentially useful properties of nontraditional configurations of intense light fields. |