Coherent vibrational and rotational dynamics of the Li_2 molecule is controlled by varying the relative phases, #phi#_n, of the rovibrational wavepacket components, |n>e~(-i(#omega#_nt+#phi#_n)). The coherent superposition is created by excitation of a set of ten rovibronic E ~(1)sum_g~(+)(#nu#_e = 12-16,J_E = 17,19) states from an intermediate state, A ~(1)sum_u~(+)(#nu#_A = 14,J_A = 18), using ultrashort optical pulses with well defined spectral amplitudes ad phases encoded into the pulse by a liquid crystal spatial light modulator. The wavepacket is probed by time-dependent photoionization and the quantum interference signal is measured as a total ionization yield. The phases of the wavepacket components are optimized to produce partial localization of the wavepacket at a given time t, in specific regions of three-dimensional space defined by the radial and angular coordinates. As a result, the ionization yield, I(t), is maximized or minimized at a time t. The degree of control achieved in the experiment(I_max-I_min)/I_max=64(+-12%). The experimental data are interpreted in terms of time-dependent radial and angular probability distributions, calculated for different initial conditions that are determined by the phase relationships in the excitation pulse.
展开▼
