Photodissociation of laser-desorbed ions as a structure determination tool.

Laser desorption Fourier transform mass spectrometry (LD/FTMS) of porphyrins, metalloporphyrins, and alkaloids is used to investigate XeCl excimer laser photodissociation of trapped ions as an alternative to collision-induced dissociation for structure analysis purposes. It is shown that the presence of an appropriate metal enhances photodissociation and that in situ metal attachment during the laser desorption event may be a useful analytical strategy. Iron-, manganese-, and chromium-attached species are examined in order to assess the effect of metal upon the propensity for photodissociation with 308-nm excitation.