Photophysical properties of 5H-dibenzo[a,d]cycloheptene in solution

A number of photophysical properties of 5H-dibenzo[n]cycloheptene have been measured including the decay parameters of the lowest excited singlet and triplet states. Molecules were excited in a two-step process. In the first step, S-1 is created which undergoes intersystem crossing to T-1, then T-T absorption creates an excited triplet molecule which returns to the first e xcited singlet level by intersystem crossing. The recreated first excited s inglet state decays back to the ground state by emitting B-type of delayed fluorescence.