Optical and ODMR Investigations of the Lowest Excited Triplet State of Dinaphtho-(2'.3':1.2); (2".3":6.7)-pyrene

Dedicated to Prof. Dr. G.-M. Schwab on his 80th birthday On the basis of the phosphorescence spectrum of dinaphtho-(2'.3':1.2); (2".3":6.7)-pyrene in n-dodecane (Shpolskii matrix) at T — 1.3 K a site and vibrational analysis was performed. With the help of ODMR measurements the symmetries of the vibrational bands were determined. In this way for most of the normal modes an assignment of the type of vibration became feasible. Because of their different zero-field splittings (ZFS) five sites could be identified. The signs of the ZFS parameters as well as the kinetic rate constants of population and depopulation of the zero-field levels (ZFL) of Ti were determined. Like the ZFS the kinetic rate constants too were different for each site reflecting different interaction of the molecules with the host matrix. Radiative and radiationless processes are discussed in terms of spin-orbit coupling (SOC).