Ultrafast vibrational dynamics in higher electronic excited states of iodine

Abstract

By using a combination of an initial pump pulse and a degenerate four-wave mixing (DFWM) process, we show that an interrogation of the vibrational dynamics occurring in high-lying electronic states of molecules is possible. As a test case, the technique is applied to iodine in experiment and in simulation. The initial pump pulse is used to populate the B ( 3 + u ) state of molecular iodine in the gas phase. By using an internal time delay in the subsequent DFWM process, which is resonant with the transition between the B state and a higher lying ion-pair state, the vibrational dynamics of the B state as well as of the ion-pair state could be observed. From the possible ion-pair states, the states of even symmetry are investigated, which are accessible by a one-photon transition from the B state. By a proper choice of the wavelengths used for the pump and DFWM beams, the dynamics of ion-pair states belonging to two different tiers are monitored. Very good agreement between experimental and theoretical results is observed in most of the studied wavelength combinations.

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“…Chen et al [132] show that these characteristics are phase sensitive and open wider opportunities to study rotational relaxation processes in molecules. By using a combination of an initial pump pulse and a degenerate four-wave mixing (DFWM) process, Liebers et al [133] show that interrogation of the vibrational dynamics occurring in high-lying electronic states of molecules is possible.…”