Enhancement of the degree of control of photofragment distributions by laser phase modulation

The possibility of enhancing the degree of control of a transient photofragment distribution achieved by means of laser phase modulation is explored. Such a control is exerted through interference between overlapping resonances, which are populated in a superposition by the laser field. It is found that by varying the central frequency of the pump laser across the energy range of the resonance superposition created, the effects of laser phase modulation on the resonance interference mechanism change remarkably, causing significant variations on the photofragment distribution. Knowledge of these variations can be used to increase and optimize the control effects of the scheme applied. The results presented here show that the intensity of the phase modulation control effect on the fragment distribution can be increased by more than double. Thus, varying the laser carrier frequency as an additional control parameter makes the control scheme more efficient and flexible.