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

A matrix consisting of nitrogen in solid argon luminesces when bombard ed by alpha-particles. The luminescence is observed to depend greatly on the nitrogen concentration. Between 185mn and 900nm the intensity o f the luminescence has a maximum for 0.9% nitrogen in argon. Wavelengt h 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-ca lled Vegard-Kaplan bands. When the concentration is such that the tota l luminescence is weak, only VK bands from the nu' = O level are obser ved but for concentrations that give strong luminescence also bands fr om 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.