The exact structure of large, biologically interesting molecules such as proteins is very important for the functions these molecules fulfill. To increase our understanding of the relationship between structure and function, and to enhance the predictive power of theoretical models, the structures of a few small model systems have been determined very precisely. Each of these model systems is closely related to important structural elements in proteins or DNA. The structure determination itself takes place by irradiating the molecules with UV laserlight and detecting which colors are absorbed by the molecule. It is found that especially the structures of systems with several chemically weak bonds differ substantially from theoretical predictions. Since the overall structure of nearly all large biomolecules is ultimately determined by these types of bonds the results presented in this thesis can be viewed as a small but important step towards a better understanding of biomolecular behavior in general.