The study of physical phenomena in nozzle flows need a precise diagnostic investigation. Thereby, Particle Image Velocimetry (PIV) is a suitable method to visualize the flow field. The aim of this thesis is to analyze the turbulent mixing layer of an axisymmetric gas jet. The streaming fluid in the nozzle as well as the surrounding fluid is air at a temperature of about 20\,\grad C. The focus is on the laser-optical analysis of the shear layer of the near-field region via PIV, to characterize the turbulent flow structures. Hence, a relation between the structures and the jet velocity is observed. According to the PIV measurements the size, position and velocity gradients of eddies are a function of the initial jet velocity. Moreover, the downstream wake of an inclined cylindrical flow obstacle, which is positioned inside the jet, is visualized from two different directions of view. Thus, insights about the occuring dead zone and the geometrical shape of the wake are gained. The dead zone area varies with time and strongly depends on the initial jet velocity. It is shown that neither the dead zone area nor the wake structure is axisymmetric. In detail, the downstream area close to the obstacle shows a complex three-dimensional shape. However, in direction further downstream this shape turns into a two-dimensional Kármán vortex street.