De-excitation processes of optically excited Nd3+ pairs in CsCdBr3

CsCdBr 3 : Nd 3+ crystals have been studied by laser selective excitation and time resolved spectroscopy. Due to the charge compensation resulting from the Nd 3+ /Cd 2+ substitution, the proportion of Nd 3+ pairs is very large and does not follow the statistical laws. This proportion has been measured, its variation with concentration has been established and the effect of codoping with a monovalent metal observed. From a comparison between the properties of single ions and pairs, energy transfers have been analysed. De-excitation channels have been determined for some excited levels from the dynamics and the relative intensities of luminescence lines. An unusual behaviour, which can lead to applications, has been observed: the 4 F 3/2 luminescence of pairs if favoured with respect to that of single ions. This behaviour is well explained Etude experimentale par des techniques d'excitation selective par laser pulse avec resolution temporelle, avec une grande proportion de Nd 3+ associes en paires, en suivant par les lois de la statistique, du fait de la substitution de Cd 2+ par Nd 3+ . Mesure de cette proportion et de sa variation avec la concentration; observation d'un effet de codopage par un ion monovalent. Analyse des transferts d'energie. Determination des chemins de desexcitation depuis quelques niveaux excites a partir de la dynamique et des intensites relatives des raies de luminescence. Observation de la luminescence du niveau 4 F 3/2 favorisee pour les paires par rapport aux ions isoles; interpretation