Coherent Phase Control Over The Reaction Of 2-Butanone And The Study Of The Cluster

We have used the method of Shapiro, Hepburn, and Brumer to control the yield rates of and . This method is based on the principle of quantum mechanical interference between two competing paths. In this case the two paths in this experiment are one- and three-photon excitation of the same state. A vacuum ultraviolet (VUV) (118nm) laser beam was produced by third-harmonic generation from an UV (355nm) beam in Xe gas. The relative phases of the two beams were controlled by passing them through a chamber containing Ar.The laser beams were focused into a molecular beam, and the ionization products were measured in a time-of-flight mass spectrometer. As the pressure of the phase–tuning gas was varied, the ionization signal was found to oscillate with a period that is proportional to the difference of the indices of refraction of the tuning gas at the UV and VUV wavelengths.In this paper the follow mechanism of ionization and dissociation, as the theory of coherent control and the results of the former experiment, was put forward by us. 2-Butanone clusters (CH₃COCH₃)_n containing up to 12 2-Butanone molecules are observed in current work. This is the largest butanone cluster ever observed in unimolecular condition. Quantum chemical ab initio calculations are carried out to determination of the structures of these butanone clusters with n=2～7. This is the first determination of the structure of butanone cluster. It is found that butanone forms cluster with a nearly perpendicular structure with n=2, while with greater n in the calculation in the work butanone cluster tends to form a circle structure which has the lowest energy which is the most stabilization.