The regions of the N-N and of the C-O stretching vibration of Ar1-x(N2
)x Mixed crystals, 0.5 < x < 1, doped with CO have been investigated b
y infrared spectroscopy. The spectra give insight into the dynamics of
the translational and rotational lattice modes. The appearance of inf
rared activity of the N-N vibron upon freezing into the quadrupolar gl
ass indicates local symmetry breaking.