The development of innovative materials with novel functional capabilities that fulfill specific application requirements is currently a very dynamic research topic. The drive for smaller and faster computers has caused a lot of focus on the development and implementation of new materials for data storage or molecular switches in recent years. However, size reduction in conventional ferromagnetic thin films becomes ever more challenging due to the risk of the loss of the magnetic state due to thermal effects. In order to overcome this limitation, efforts are being put into the research and development of molecule-based devices. Therefore, the design of molecular analogs that are capable of operating at room temperature and are stable over successive cycles is required. In addition, such devices have to work with conventional power supplies and should have a short addressing time. Promising candidates that fulfill all these conditions are spin crossover (SCO) materials which are at the center of this thesis. This thesis aims to firstly, identify suitable SCO materials for a novel approach to SCO-based deformation sensor systems, secondly, investigate the vibrational modes that influence the SCO properties upon optical excitation with optical pump – nuclear inelastic scattering (NIS) probe experiments and thirdly, study the cooperativity within SCO films.weiterlesen