Electronic and Vibrational Anisotropy in Molecular Wavepacket Dynamics

Resonant excitation of an isolated molecule typically results in an anistropic distribution of molecular axes in the excited state - alignment or orientation of the molecules in the laborotory frame. Femto- or attosecond laser pulses with broad enough bandwidths can potentially excite several electronic and vibrational states in a molecule. By appropritately coupling the angular momentum of these states, we find that an evolving anisotrpy (alignment or orientation) develops in the electronic and vibrational probabilty distributions, in adition to axis alignment. The evolution of the electronic and vibrational alignment is synchronized with vibronic dynamics occuring in the molecular frame, and can be orders of magnitude faster than molecular rotation. This anisotropy can in princiapal be measured by time and angle resolved scattering. A measurement of the evolving electronic anisotropy in resonantly excited ammonia by time and angle resolved photoelectron spectroscopy confirms the theoretical analyasis.