  Based on the Mie theory and on the incident beam model via superposition of
two plane waves, we analyze numerically the momentum flux of the field
scattered by a spherical microparticle placed within the spatially
inhomogeneous circularly polarized paraxial light beam. The asymmetry between
the forward- and backward-scattered momentum fluxes in the Rayleigh scattering
regime appears due to the spin part of the internal energy flow in the incident
beam. The transverse ponderomotive forces exerted on dielectric and conducting
particles of different sizes are calculated and special features of the
mechanical actions produced by the spin and orbital parts of the internal
energy flow are recognized. In particular, the transverse orbital flow exerts
the transverse force that grows as a^3 for conducting and as a^6 for dielectric
subwavelength particle with radius a, in compliance with the dipole mechanism
of the field-particle interaction; the force associated with the spin flow
behaves as a^8 in both cases, which testifies for the non-dipole mechanism. The
results can be used for experimental identification and separate investigation
of the spin and orbital parts of the internal energy flow in light fields.
