LUMINESCENCE FROM MATRICES OF NITROGEN AND ARGON EXCITED BY ALPHA-PARTICLES

A matrix consisting of nitrogen in solid argon luminesces when bombarded by alpha-particles. The luminescence is observed to depend greatly on the nitrogen concentration. Between 185mn and 900nm the intensity of the luminescence has a maximum for 0.9% nitrogen in argon. Wavelength resolved measurements show that the spectrum mainly consists of N-2 bands from the A(3) Sigma(u)(+)-X(1) Sigma(g)(+) transition, the so-called Vegard-Kaplan bands. When the concentration is such that the total luminescence is weak, only VK bands from the nu' = O level are observed but for concentrations that give strong luminescence also bands from nu' > O appear intensively. With a concentration of 50% nitrogen in argon nearly all the luminescence comes from the atomic nitrogen D-2-S-4 transition at 523 nn.