LUMINESCENCE SPECTRA OF MATRIX-ISOLATED N-2 AT HIGH-PRESSURE AND LOW-TEMPERATURE

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) Sig ma(g)(+)) was investigated as a function of pressure (<30 GPa), temper ature (300 K and 77 K), and matrix material. Observed UV transitions w ere interpreted as rovibronic transitions of the impurity molecule alo ng 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-indu ced shifts of electronic bands by two mechanisms: a dielectric effect and a volume effect. (C) 1997 American Institute of Physics.