High-order harmonic generation in laser aligned molecules

Summary form only given. High-order harmonic generation (HHG) has been widely studied in atoms. More recently it has been shown that molecules introduce a variety of additional features to HHG. In particular, unlike atoms, molecules are not isotropic systems. It is known that processes such as multiphoton ionisation can be strongly influenced by the angle between the laser electric field vector and the molecular axis and it is therefore natural to ask if there is any orientation dependence in the closely related process of HHG. We demonstrate molecular alignment control in high density vapours of CS/sub 2/, hexane and N/sub 2/ using the electric field of a 300 ps duration laser pulse.