The photodissociation of ClNO: a computational approach

The detailed photodissociation dynamics of ClNO on the 2 ¹ A' and 1 ³A'' states have been investigated using computational methods. Chapter 3 concerns the photodissociation of the 2 ¹A' state. New, purely ab initio potential energy surfaces are described, calculated using the MRCI method. Transition dipole moments and non-adiabatic coupling matrix elements have been calculated across the extent of the surface. To investigate the dissociation dynamics, wavepacket propagations using the MCTDH method have been performed, yielding NO product state distributions which match extremely well with experimental results. In addition, classical trajectory calculations incorporating surface hopping have modelled transitions through a conical intersection in the asymptotic region of the surfaces, and have allowed anisotropy parameters to be obtained.
In chapter 4 the photodissociation dynamics of the 1 ³A'' state are described. A new potential energy surface and set of transition dipole moments have been calculated, and these have been used in quantum and classical dynamics calculations. In this case, whilst the quantum results agree well with experiment, the classical results do not.
In chapter 5, coherent control on the 1 ³A'' state is discussed. Using the MCTDH method, both transform limited and shaped ultrashort laser pulses at a series of energies have been used to influence the dynamics. The NO vibrational and rotational state distributions can be changed considerably using femtosecond pulse pairs separated by a variable delay.
Finally, chapter 6 examines the effect of spin-orbit coupling on the states of ClNO and surfaces taking this into account have been obtained at the CASSCF level. These surfaces are used to qualitatively explain experimental product state distributions. Further to this, dissociation on the spin-orbit equivalent of the 2 ¹A' state has been studied using a preliminary wavepacket propagation; the predicted spin-orbit product state distributions agree well with experiment.