The Photodissociation Dynamics Studies Of Methyl Nitrite

When the methyl nitrite CH3ONO is excited by photon, the dominant photofragments NO and methoxy radicals CH3O are produced in these dissociation channels. The radicals NO and CH3O are important intermediates in both combustion and atmospheric chemistry. The photodissociation study of the molecule CH3ONO not only provides some useful information for an understanding of the bondbreaking processes in polyatomic molecules, but also probes a wide range of dynamic interaction responsible for the dissociation of polyatomic molecules.The complete description of molecular photodissociation requires the knowledge of the scalar and vector properties of the photofragments or parent molecule. The scalar and vector properties can provide some important information to understand the dynamics of the dissociation process better. In this thesis, the photodissociation dynamics of methyl nitrite (CH3ONO) was studied using single photon laser-induced fluorescence method on two excited states. The internal energy distribution of the photofragments and the vector correlation between the electronic transition dipole moment involved in the absorption of the parent molecule and the rotational angular momentum of the photofragments were obtained. The main results are as follows:The laser induced fluorescence spectroscopy of the ground state CH3O(X 2E v"=0, 1) fragments by the photodissociation of CH3ONO at 355 nm hasbeen recorded firstly. Integrating our results with the results of other experiments and theoretical model, the all energy distribution of the photofragments by the photodissociation of CH3ONO at 355 nm can be found clearly. We simplified the theoretical treatment that determines the alignment of a symmetric top molecule andused it for our concrete experimental configuration. The rotational alignment of five-atomic molecules CH3O was measured firstly. The positive alignment parameter indicated that the angular momentum vector of the recoiling CH3O fragments was aligned parallelly to the transition dipole moment associated with the 355 nm photodissociation of the CH3ONO.After the photodissociation of CH3ONO at 266 nm, the measured relative population of the photofragment NO v" = 0 : 1 : 2 : 3 was 0.50 : 0.22 : 0.16 : 0.12. The rotational and vibrational energy of the photofragment NO were distributed with 13 1% and 11 1% of the total available energy, respectively. The negative alignment parameter and the preferential population of the II" doublet state of the photofragment NO indicated that the angular momentum vector of the recoiling NO fragments was aligned perpendicularly to the transition dipole moment associated with the 266 nm photodissociation of the CH3ONO.