10th European workshop on laser ablation

Abstract

Since the development of lasers 50 years ago, laser ablation, as a sampling technique for direct emission spectroscopy (LIBS) or in combination with inductively coupled plasma atomic emission spectrometry (LA–ICP–AES) or inductively coupled plasma mass spectrometry (LA–ICP–MS), has become a very attractive and efficient sampling technique for direct analysis of solids. The combination with ICP–MS, first introduced by Gray in 1985, has, especially, attracted much attention in the past 25 years and much progress has been reported. The direct and high-spatial-resolution analysis of major, minor, and trace elements and isotope-ratio determinations make the technique widespread and applicable to a wide variety of fields of research. The driving force of LA–ICP–MS has been geochemistry, which remains one of the major fields of application of this technique. However, the technique is gaining more attention in material science, biology, medical and forensic sciences, and archaeology. This is mostly because a large number of uncertainties during the ablation, transport, and excitation of laser-generated aerosols have been studied and have been substantially reduced, so that quantitative results with very good precision and accuracy can be achieved. This is mainly because of technological progress in laser technology. Today, almost all wavelengths used in LA– ICP–MS are in the low UV region, which enable representative sampling of a large number of materials. The short wavelength of 193 nm introduced in 1995 is well established and very successful in representative sampling of all non-conducting samples. In addition, the use of femtosecond laser ablation, with very short pulses, improved the sampling of conducting samples and substantially increased the field of applications . Most interesting, a number of applications have been reported in which non-matrix matched calibration strategies have been successfully applied. This feature, in particular, which is rather difficult to perform in other direct solid analysis techniques, makes the use of laser ablation very attractive. In conclusion, LA–ICP–MS for insitu analysis of solids can be placed in the same group of successful analytical techniques as ICP–AES or ICP–MS for liquid sample introduction. From the beginning of LA–ICP work, research was directed in two major directions: fundamental and applied studies. The fundamental research focused on the ablation process itself—the interaction of laser light and matter. Progress was made with regard to understanding the energy transfer, plasma generation, formation of particles (laser aerosol) from this plasma, and their transport phenomena. After the initial use of IR lasers low-UV became the spectral range of choice. A gradual reduction of wavelength from 1064 nm, via 266 nm and 213 nm, towards 193 nm improved the performance of LA units substantially. This is because of reduction of thermal effects at the site of ablation, making generation of the aerosol more tolerant of the actual sample composition. Applied studies contribute to a deeper understanding of geochemistry, material and biomedical sciences, and take advantage of the direct analysis of samples at micrometer spatial resolution. More Published in the special issue Laser Ablation, with Guest Editors Dieter Garbe-Schonberg, Jan Fietzke, and Detlef Gunther