The molecular dynamics of dendrimer branches were studied by observing the excimer formation of pyrenyl end-groups. By a selective synthesis only one pyrene moiety per dendron was attached, resulting in a dendrimer with 3 fluorophors per molecule. The first 3 generations of the dendrimer were synthesized by the convergent-growth approach. By time resolved measurements of the excimer and monomer fluorescence an increased mobility of the end-groups was observed.