New means of spatially manipulating molecules with light

We develop a general framework for describing the interaction of molecules with a nonperturbative intensity gradient and note several limits, including the two-level Hamiltonian of atom trapping and the quasistatic Hamiltonian of molecular optics. The theory is used to propose a new molecular optics scheme which complements previous work in the area of spatial manipulation of molecules in intense fields by introducing the possibility of reflecting molecules with light. Repulsive interaction obtains in the limit of small level spacings as compared to the field frequency, attained by exciting the molecules to high Rydberg states. Some of the potential applications of the repulsive interaction are illustrated and others are noted. We address the problem of molecular alignment in intense laser fields and describe the possibility of simultaneously focussing the center-of-mass motion of molecules and aligning their figure axis after exit from the laser focus, under field-free conditions. (C) 1999 American Institute of Physics. [S0021-9606(99)00134-8].