N-2 molecules with a concentration of ca. 1% were isolated in Xe, Kr, and Ar. X-ray stimulated luminescence (A (3) Sigma(u)(+) --> X (1) Sigma(g)(+)) was investigated as a function of pressure (<30 GPa), temperature (300 K and 77 K), and matrix material. Observed UV transitions were interpreted as rovibronic transitions of the impurity molecule along with phonon sidebands as lattice excitations. Spectra were analyzed due to band maxima of vibron progressions, bandwidth, and bandshape, Franck-Condon profiles, and molecule constants, each as a function of pressure. The main result was a shift of band maxima with pressure to lower energies at a rate of 100 cm(-1)/GPa in Xe, 50 cm(-1)/GPa in Kr, and 10 cm(-1)/GPa in Ar. We modeled and explained these pressure-induced shifts of electronic bands by two mechanisms : a dielectric effect and a volume effect.