Optimal control of vibronic population inversion with inclusion of molecular rotation

This paper considers vibronic population inversion in the presence of molecular rotation. The objective is to invert the population of a vibronic level with populated rotational levels to a specific vibrational level in the excited electronic state regardless of the detailed population distribution in the final rotational levels. The control of the multilevel population inversion is achieved by design of a pump pulse through optimal control theory. The total energy fluence and the pulse peak intensity are imposed as physical constraints in the design cost functional. A model diatomic molecule is used as an example to investigate molecular rotational effects on the vibronic population inversion and the control properties at different target times. The numerical results indicate that the shape-optimized pulses can achieve nearly complete population inversion and largely overcome the difficulty that a rectangular pulse faces due to energy mismatches and multiple dipole transition moments.