Achieving of high selective excitation of metastable states in atomic systems is one of the most desired results in collisional physics. Common procedures used for preparation of selectively excited atomic beams are based on the properties of certain atomic-atomic and atomic-ionic scattering processes. Such approaches, however, are not effective enough for many applications. Recent progress in laser technique, as well as in theoretical understanding of multiphoton processes in atoms [1, 2] makes it possible to introduce novel methods for effective selective excitation of metastable atomic states by short laser pulses.
In the present work the possibility to achieve high selective excitation of metastable states of atoms by interaction with short laser pulses with reasonable parameters is demonstrated theoretically. Interactions of hydrogen atom with femto- and attosecond laser pulses are studied with the use of well established close-coupling approach [1-3]. The parameters of laser pulses which lead to high selective excitation of metastable state of atom together with small ionization probability are calculated with the use of different kinds of optimization procedures.
For the interaction time of order of hundred femtoseconds the optimal laser field is found to consist of few femtosecond pulses. It is also found that high selective multiphoton excitation of metastable state with very small ionization probability can be achieved by a single femtosecond pulse with Gaussian-like envelope. The Raman type transitions play an important role in the process.
If interaction time reduces to few femtoseconds the optimal laser field transforms into a grid of attosecond pulses. A distinct physical explanation of such a transformation is proposed. The parameters of attosecond laser pulses grids that lead to high final metastable state population with photoionization suppressed are calculated.

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