  We demonstrate that the thermal Casimir-Polder forces on molecules near a
conducting surface whose transition wavelengths are comparable to the
molecule-surface separation are dependent on the ambient temperature and
molecular polarization and they can even be changed from attractive to
repulsive via varying the temperature across a threshold value for
anisotropically polarizable molecules. Remarkably, this attractive-to-repulsive
transition may be realized at room temperature. Let us note that the predicted
repulsion is essentially a nonequilibrium effect since the force we calculated
on a ground-state (or an excited-stated) molecule actually contains the
contribution of the absorption (or emission) of thermal photons.
