Applications of LEIS in Catalysis

Several authors believe that comparing LEIS spectra of one sample measured at different primary ion energies may also provide a means of determining which atoms are in the outer layer, and which are in the subsurface region [53-55], Because these arguments are based on a rather persistent misunderstanding, the 

LEIS has been applied to study the surface composition of Co-Mo and Ni-Mo hydrodesulfurization catalysts [58-60], Fe-based Fischer-Tropsch [61], automotive exhaust catalysts [62], ammonia synthesis catalysts [63], and of model systems such as Pt evaporated on Ti02 [64] and Au and Pd on thin Si02 layers [65]. In this respect, the review of Horrell and Cocke [66] describes several applications. 

In conclusion, LEIS is extremely surface-sensitive, and suitable for determining the outer layer compositions of catalysts and alloys, provided that proper calibration can be achieved. The shape of the background contains information over the vertical distribution of elements in the surface region. 

Fundamentals of Surface and Thin Film Analysis. North Holland, New York, 1986. 

Benninghoven, F.G. Riidenauer, and H.W. Werner, Secondary Ion Mass Spectrometry, Basic Concepts, Instrumental Aspects, Applications and Trends. Wiley, New York, 1987. 

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