Laser ablation synthesis of new phosphorus and phosphorus-sulfur clusters and their TOF mass spectrometric identification

Laser ablation of elemental phosphorus, sulfur, their mixtures or some phosphorus sulfides in connection with Time-Of-Flight (TOF) mass spectrometry was studied. Laser ablation of pure red phosphorus leads to formation of singly charged P-n(+) (n = 1-189) and P-n(-) (n = 1-225) clusters. Much higher n values than those known in the literature were proved. Similarly, laser ablation of elemental sulfur produces S-m(+) (m = 1-11) and S-m(-) (m = 1-15) species. Via laser ablation of P4S3 and P4S10 compounds, the formation of several clusters with different P:S ratio was observed. Their stoichiometry was estimated from the mass spectra and natural abundance of sulfur isotopes. Similarly to laser ablation of red phosphorus, the amounts of PnSm clusters generated from P4S3 and P4S10 with an odd number of phosphorus atoms were much higher than those with an even number. Generation of various mixed P-S clusters was also reached via direct laser ablation of a mixture of the elements. Higher yield of the mixed clusters was obtained when the mixture was first homogenized using ultrasound. Partially, some reactions were also initiated by ultrasound itself. Totally, at least 68 new PnSm clusters were formed and detected. The laser ablation synthesis either from phosphorus sulfides or from elemental mixtures represents a new possibility of forming and studying mixed clusters of these elements. (C) 2004 Elsevier Ltd. All rights reserved.