Laser desorption ionization versus electrospray ionization mass spectrometry: Applications in the analysis of cluster anions

Mass spectra of transition metal carbonyl cluster anions were recorded usin g laser desorption ionization time-of-night (LDI-TOF) and electrospray ioni zation (ESI) techniques. The LDI spectra generally contain peaks correspond ing the intact cluster together with extensive CO loss fragments ions where as the ESI spectra exhibit peaks corresponding the intact cluster together with few (if any) CO loss fragment ions. The parameters of both techniques can be modified to vary the extent of fragmentation. In all cases no fragme ntation of the metal core is observed. Overall, ESI is a more informative m ethod for the analysis of these types of cluster anions.