PHOTOIONIZATION AND PHOTODISSOCIATION OF LASER-VAPORISED METALLOTETRAPHENYLPORPHYRINS

The photoionisation and photodissociation processes induced by 193 and 266 nm excitation of a series of metallotetraphenylporphyrins (NiTPP, ZnTPP, CoTPP, CuTPP, and VOTPP) have been investigated, using laser-d esorption laser-photoionisation time-of-flight mass spectrometry. At 1 93 nm, all of the molecules undergo molecular photoionisation followed by photo-fragmentation (class A behaviour). At 266 nm, ZnTPP and CuTP P exhibit class A behaviour, whereas NiTPP, CoTPP and VOTPP undergo ne utral photodissociation followed by ionisation (class B behaviour). Ne utral photodissociation results in cleavage of the coordinated metal f rom the macrocycle, whereas photodissociation of the molecular ion lea ds to loss of phenyl substituents from the macrocycle without loss of the metal atom.