We have theoretically studied the effect of chirping one-photon incident laser pulses on (I) the branching ratio of the HOD molecule in the photochemical reaction D + OH<--HOD-->H+OD and (II) the UV photodesorption dynamics of NH3 and ND3 from Cu(111). As was predicted in our previous 1D model, wave packet calculations have demonstrated that it is possible, in practice, to control the branching ratio of reaction (I) and to greatly enhance the desorption probability of the photodesorption reaction (II) by negatively chirped laser pulses. It was found that two characteristics of (negatively) chirped laser pulses contribute to this remarkable effect; the mechanism of adiabatic rapid passage for the population transfer between the ground and excited states, and the intrapulse pump-dump process for determining the branching ratio and photodesorption yield.