Vibrational ladder climbing in NO by (sub)picosecond frequency-chirped infrared laser pulses

The anharmonic vibrational ladder of nitric oxide (NO) is climbed by irradiating the molecule with chirped intense (sub)picosecond infrared (IR) pulses (1_max=1.0 X 10¹⁰ W/cm²). The chirp of the broadband IR (hv = 1850 cm^-1, Dhv =50 cm ^-1) pulse from a free-electron laser is controlled by a pulse shaper. Transfer up to the excited vibrational state X²P_1/2(v= 3) of NO shows a strong enhancement when the frequency chirp of the IR pulses follows the consecutive anharmonic vibrational transitions.