  The universal mechanism of trapping and localization of sufficiently
slow-speed particles by a potential well deepening with time is established on
the basis of fundamental relations of classical mechanics. Such wells may be
created for a wide range both charged and neutral particles (with electric or
magnetic moments) by means of a controllable electromagnetic field with growing
strength (up to a certain moment) but with a fixed spatial distribution.
Detailed analysis of features of corresponding electromagnetic traps of
particles is carried out on the visual example of the one-dimensional
rectangular potential well deepening with time. Obtained results may be used in
ultrahigh resolution spectroscopy of various microparticles (including atoms,
molecules and ions).
