|
|
|
|
|
|
High Harmonic Generation (HHG) has been used for many years as a source for vacuum ultraviolet and soft X-ray light. The process of HHG is usually divided into three steps: 1) during the interaction of an intense laser field with an atom, part of the electron wave function tunnels out of the atom, 2) is afterwards accelerated in the electric field of the laser and 3) eventually recombines with the mother atom, releasing its kinetic energy into photons. Recently, a method to resolve molecular structures using the short de Broglie wavelength of the recombining electron wave packet has been discussed.
We have performed HHG on aligned nitrogen molecules in our newly setup lab in the PULSE center. The alignment is achieved via the interaction with a further nonresonant laser pulse via Raman like interaction. In addition to simple spectral measurements of the HHG, we measured the phase of the high harmonic radiation by using argon as a reference gas. We compare our experiments to simulations including rotational alignment and HHG and discuss the structural resolution within the framework of a two-center interference model.
Finally, we give an outlook on HHG on excited electronic states to study Conical Intersections.