Vibrational ladder climbing in NO using ultrashort IR laser pulses

Chirped excitation of an electronic ladder system has shown complete transfer of the population to the top-level of the ladder system. Similar excitation of vibrational ladders in molecules may provide a tool for state-selective chemistry. Experimental results on the climbing of the anharmonic vibrational ladder of nitric oxide (NO), by irradiating the molecule with femtosecond infrared (IR) pulses, are presented. The free-electron laser FELIX is tuned to lambda = 5.3 mu m with a bandwidth of Delta lambda = 0.3 mu m, corresponding to a pulse duration of 150 femtoseconds. Transfer to the excited states of NO is monitored by 1+1 REMPI. Population is found up to v = 5, the highest level within reach of the IR bandwidth. The average transfer per step of the ladder is found to be 17%.