The 248 nm photodissociation of DOCl: laser excitation fluorescence spectra of OD

The dynamics of the 248 nm excimer-laser-induced photodissociation of DOCl has been investigated by the observation of the OD fragment by laser excitation fluorescence. The OD PI(A') lambda doublet state is strongly favoured in the dissociation and there is a small preference for the 2-PI-3/2 spin-orbit state. The observed OD rotational distribution differs for the two lambda doublets, and for the PI(A') component of the 2-PI-3/2 spin-orbit state the distribution is Gaussian. The results are interpreted in terms of a fast dissociation with most of the energy released into relative translational energy. The rotational distribution can be explained with a Franck-Condon type model

Surface second harmonic generation studies of the dodecane/water interface: the equilibrium and kinetic behaviour of p-nitrophenol and tri-n-butyl phosphate

The behaviour of p-nitrophenol (PNP) absorbed at the dodecane/water interface and the interaction with tri-n-butyl phosphate (TBP) were studied by surface second harmonic generation (SHG). The polarisation dependence of the PNP SHG signal, which is the same for all concentrations of PNP and TBP, is best described in terms of a limiting weak orientational order. In the presence of TBP, the SHG signal initially increases with PNP concentration, passes through a maximum and then it decreases. At low PNP concentrations, increasing the TBP concentration leads to an increase in the SHG intensity, but for higher PNP concentrations the intensity decreases. The free energies of adsorption for PNP and TBP to the dodecane/water interface were determined using Frumkin and Langmuir isotherms. The kinetics of the interaction between TBP and PNP was observed by monitoring the SHG signal along a liquid-liquid flow cell and found to be first-order at high interfacial coverage with rate constant, k, of 0.1 +/- 0.01 s(- 1)

266 nm Photolysis of HOCl and DOCl: laser-excitation fluorescence detection of OH and OD

Fragment rotational population distributions for OH and OD were observed by laser-excitation fluorescence following the 266 nm photolysis in a free jet molecular beam of HOCl and DOCl, respectively. The photodissociation dynamics show a strong preference for the 2PI(A') OH or OD lambda doublet component in both spin-orbit states. The 2PI3/2 state is more populated than the 2PI1/2 State of OH. The distributions are consistent with photolysis via a repulsive excited state and the measured rotational alignment (-0.28) is compatible with an excited- state symmetry of A' for the dominant dissociation pathway. The high-J limiting value for the degree of electron alignment reaches the extreme value of - 1 for the 2PI1/2 state for both OH and OD, but falls short of this for the 2PI3/2 state, reaching only -0.7