Selective vibrational excitations in the OX (X = F, Cl, Br, I) molecules

Using ab initio calculated potential energy and electric dipole moment functions for the X(2)Pi states of OF, OCl, OBr and OI, two models have been tested to selectively populate their vibrational modes by ultrashort coherent light pulses. For a given form of the pulses either a perturbative approach using discrete vibrational eigenstates and electric dipole transition moment matrix elements or a wavepacket propagation technique were used. The optimisation of the pulse parameters and the mechanisms of the multiphoton processes are discussed. For the target level v=10 populations of more than 60% have been achieved in all four molecules. For OCl it was possible to populate selectively all target levels between v=2 and v=15 using chirped pulses.