LASER-ABLATION FOURIER-TRANSFORM MASS-SPECTROMETRIC STUDY OF ZEOLITES

Laser ablation (1064 nm) Fourier transform mass spectrometry has been used to study the sodium ion-exchanged LTA (Na-A) and MOR (Na-M) zeoli tes and the potassium ion-exchanged LTL (K-L) zeolite. When the ion-ex changed element is taken into account, the positive-ion and negative-i on laser ablation Fourier transform mass spectra from all three zeolit es are similar and apparently independent of the zeolite structure. Wi th the exception of small atomic and diatomic ions, the anions detecte d from the laser ablation of the zeolites are of the form M(SiO2O- (wh ere M=H, Na, K, AlO and x=1-5). The laser ablation mass spectra show a strong dependence on laser power, with the higher Si/Al ratio zeolite , mordenite, exhibiting the highest stability under 1064nm laser irrad iation.