  Recently a new time-evolution picture of the Dirac quantum mechanics was
defined in charts with spatially flat Robertson-Walker metrics, under the name
of Schr\"{o}dinger picture [I. I. Cot\u{a}escu, arXiv:0708.0734] . In the
present paper new Dirac quantum modes are found in moving charts of the de
Sitter spacetime using the technical advantages offered by this picture. The
principal result is a new set of energy eigenspinors which behave as polarized
plane waves and form a complete system of orthonormalized solutions of the free
Dirac equation.
