The early stages of crystal formation are an important issue in zeolite science. Especially the nucleation step causes major problems in experimental investigations. In this work electrospray ionization mass spectrometry (ESI-MS) is used as a quite
novel technique to monitor the solid state formation process of aqueous silicates leading to zeolites like silicalite-1. The formation of specific structures is directed by organic additives like tetrapropylammonium (TPA). Up to now it is unclear at which
stage in the solid-state formation process the template molecules exert their structure-directing. The results of this dissertation suggest a pathway of particle formation via amorphous intermediates which would recrystallize rather than a direct assembly
process of defined silicate oligomers. Moreover, using isotopically labeled silicate atoms interconversion reactions between silicate species have been proved to be concerted, involving several silicon atoms simultaneously.