Laser-Assisted Intermolecular Energy Transfer between Electronic States of Carbon Monoxide in the Vacuum Ultraviolet

We report the first observation of laser-assisted collisions in molecules. Cross sections for such intermolecular processes involving high-energy ($E\sim 11$ eV) Rydberg states in carbon monoxide are shown to be larger than ${10}^{-16\mathrm{}}$ ${\mathrm{cm}}^2$ at the laser intensities approaching ${10}^{10}$ W/${\mathrm{cm}}^2$. Our experiments clearly illustrate the care necessary in interpreting multiphoton spectra taken at high laser powers.