Sur une similitude entre des agrégats obtenus en émission ionique secondaire et des molécules observées en astrophysique

Abstract

A comparison is made between linear interstellar molecules HC x N observed only for odd x and C n H − ions obtained in SIMS experiments which are very much profuse for even n than for odd ones. These two kinds of clusters are isoelectronic if n=x+1. So the study of the C n H − ion properties with the Huckel method lets to get easily some results on HC x N molecules and to understand why only the odd ones are detected in interstellar clouds: the Fermi level of these clusters indeed falls into a band of degenerated π levels; so according to the carbon atom number parity, it is either full up to even n or odd x (great stability of the cluster) or half-filled in the other case (weaker stability of the corresponding cluster). C n H + ions and C n H molecules are considered too Comparaison des molecules interstellaires HC x N lineaires, observees seulement pour x impair, et les ions C n H − , obtenus par experiences SIMS et beaucoup plus abondants pour n pair que n impair. Calculs de Huckel pour les systemes isoelectroniques, lorsque n=x+1, sur C n H − et aussi sur HC x N, observe dans les nuages interstellaires avec x impair