  From long time transverse and longitudinal optical forces are used for
non-contact and noninvasive manipulation of small particle. The following
question arises: What is the impact of these forces on the continuous media as
air and silica. In this work we obtain analytical expressions for radiation
force and radiation potential in dipole approximation of laser pulses
propagating in dielectric media. The longitudinal force is proportional to the
second time derivative of the intensity profile. At fixed initial energy of a
laser pulse, as shorter is the pulse as bigger is the force. It is possible the
neutral particles in gases and solids be confined in the pulse envelope and to
move with group velocity. In silica the longitudinal force of a femtosecond
pulse is of few order of magnitude greater than molecular forces. Thus, the
ablation in silica can be realized through broken molecular connections.
