Generation of novel AumSen clusters via laser ablationsynthesis. Laser desorption ionisation time-of-flight massspectrometry

Several gold selenium complexes are known (e.g., [Au 2 (Se 2 )(Se 3 )] 2- , [Au 2 (Se 2 )(Se 4 )] 2- and [Au 2 Se 2 (Se 4 ) 2 ] 2- ). Minerals such as fischesserite (Ag 3 AuSe 2 ), kurilite ((Au,Ag) 2 (Te,Se,S) 2 ) and petrovskite ((AuAg)(S,Se)) are found in nature. Laser desorption ionisation time-of-flight mass spectrometry (LDI TOF MS) is powerful technique to generate and study clusters formed during laser ablation of various materials leading to metal chalcogenides [1] or gold carbides [2], for example. The aim of this work is to study the generation of Au m Se n clusters via laser ablation synthesis (LAS) using mixtures of GNPs (or auric acid) with selenium in various molar ratios as precursors. We have found that GNPs are chemisorbed on selenium surface leading to the formation of a kind of nano-composite as confirmed by scanning electron microscope (SEM) analysis. The LAS from various precursors and nano-composites leads to the generation of several series of Au m Se n clusters which stoichiometry was determined. Example of mass spectra showing some of the detected Au m Se n clusters is given in Fig. 1. Over 30 new gold selenide clusters were identified: AuSe 2- , AuSe 3- , AuSe 4- , AuSe 5- , AuSe 6- , AuSe 7- , AuSe 8- , AuSe 9- , AuSe 10- , Au 2 Se - , Au 2 Se 2- , Au 2 Se 3- , Au 2 Se 4- , Au 2 Se 5-, Au 2 Se 6-, Au 2 Se 7- , Au 2 Se 8- , Au 3 Se - , Au 3 Se 2- , Au 3 Se 3-, Au 3 Se 4- , Au 3 Se 5- , Au 4 Se - , Au 4 Se 2- , Au 4 Se 3- , etc. Understanding the nature and chemistry of such clusters can inspire the development of novel routes for the synthesis of new compounds. Example of possible stabilization strategy has been reported for the [NaAu 12 Se 8 ] 3- complex [3]. Computed structures of selected gold selenides generated in this work via LAS are given in Fig. 2. Concluding, (i) LAS is advantageous technique to generate novel un-usual gold selenides and (ii) the stoichiometry of Au m Se n clusters generated might inspire synthesis of new Au-Se materials with unique properties.