Formation of molecular Rydberg states in an intense laser field

In this paper, we experimentally study the decay constants and the Rydberg states population of molecular ions generated in a strong laser field by using a time-of-flight mass spectrometer. The lifetime of molecular ions is determined by tuning the initial velocity of the aimed ions into the free flight zone of the mass-spectrometer, which is a facile and straightforward method. The lifetime of CO+ is 13.91 +/- 5.31 mu s, while that of CO2+ is 6.68 +/- 1.41 mu s. The lifetime of H-2(+) , H2O+, and O-2(+) are 2.93 +/- 1.25 mu s, 4.01 +/- 0.52 mu s, and 5.22 +/- 1.93 mu s. Part of the molecular ions are populated in the Rydberg states, and the distribution of their populations in the Rydberg states is achieved via precise calibration of the dc field of the acceleration region.