Laser microprobe mass spectrometry (LMMS) aims at the identification of local organic and inorganic constituents at the surface of solids. The low mass resolution capabilities of the initially used time-of-flight (TOF) mass spectrometers have often proved to be insufficient for identification. Therefom, high mass resolution Fourier transform (FT) LMMS was developed. Neo-ceramic powders with oxide or carbide coatings were analyzed by both liT LMMS and TOF LMMS. The data are useful to compare the analytical information gained from both methods. Analytical results of these samples by electron microprobe x-ray analysis (EPXMA) and secondary ion mass spectrometry (SIMS) are discussed to assess the place of liT LMMS and TOF LMMS in the spectrum of microanalytical techniques.
Ceramic materials are widely used in in an ever-increasing number of applications due to their favourable mechanical and electrical features in companion with metals. One of the important disadvantages of ceramic materials for material processing is their brittleness. For the most part, this problem may be overcome by the addition of certain substances, possibly as coatings, followed by hot isostatic pressing or sintering. The high temperatures and pressures applied in these methods reduce the porosity of the material, which is the main cause of its brittleness. The use of coated powders promotes better cohesion of the particles during the sintering process, which thus produces more-solid and homogeneous materials. The investigation of the coating and its characteristics requires the application of modem techniques for local and surface analysis.
Laser microprobe mass spectrometry (LMMS) uses a focused laser beam to evaporate and ionize a microvolume at the surface of solids. The method provides elemental and molecular information about the upper layers of the sample on a micrometer scale. It requires virtually no sample preparation and can be applied to non-conducting materials. Lateral resolution is, in practice, 1-5 pm. A recent Literature survey demonstrates that the strength of LMMS resides in the qualitative characterization of inorganic as well as organic surface components.'-' Initially, time-offlight (TOF) instruments were used because of their high transmission and the momentary nature of the ionization by the uv laser pulses. However, it tums out that the low mass resolution capabilities of TOF LMMS do not permit the full exploitation of the potential of a focused laser for practical identification purposes. Therefore, recent developments have involved the use of Fourier transform (FT) mass analyzers in LMMS.3-S An important question to address concerns the extent to which the additional information and specificity gained from high mass resolution mass spectrometry really outweighs its drawbacks, such as the need for more sophisticated instrumentation, possibly lower sensitivity and more complicated operational procedures. The technologically important analysis of coatings on neo-ceramics was therefore taken as a practical test cast to compare the application of TOF and of F T LMMS with an external Author for correspondence.
source. Additionally, data were obtained from the same samples by electron microprobe X-ray micro-analysis (EPXMA) and dynamic secondary ion mass spectrometry