  The class of transition metal compounds shows an enormous richness of
physical properties, such as metal-insulator transitions, colossal
magneto-resistance, super-conductivity, magneto-optics and spin-depend
transport. It now becomes more and more clear that in order to describe
transition metal compounds the charge, orbital, spin and lattice degrees of
freedom should all be taken into account. With the recognition that the local
orbital occupation plays an important role in many of the transition metal
compounds there is a need for experimental techniques that can measure the
orbital occupation. This technique is soft x-ray absorption spectroscopy.
Within this PhD. Thesis we will illustrate the usefulness of this technique by
some examples: 1) Magnetic versus crystal-field linear dichroism in NiO thin
films. 2) The importance of spin-orbit coupling in CoO bulk and CoO thin films.
3) Aligning spins in anti ferromagneticfilms using antiferromagnets. 4) The
spin-state puzzle in the cobaltates. 5) Determination of the orbital momentum
and crystal-field splitting in LaTiO3. 6) Orbital-assisted metal-insulator
transition in VO2.
