应用 RAMAN 和 LIBS 对汽车油漆样品的深度扫描.pdf

Application Note - Forensics 2 Depth scans on car paint samples with Raman spectroscopy and LIBS Lutz Pfeifer, Saskia Damaske, Wolfgang Werncke and Virginia Merk LTB Lasertechnik Berlin Introduction The combination of Raman spectroscopy with laser-induced breakdown spectroscopy (LIBS) has the advantage of coupling two complementary analytical methods: with LIBS it is possible to obtain information about the elemental composition of a sample at the examination point, while Raman spectroscopy reveals the molecular, crystalline or mineralogical structure. Another benefit of combining Raman/LIBS measurements is the opportunity to achieve depth information. Namely, characterization of a sample’s constitution when penetrating the surface with repeated laser ablations at the same point. This specific advantage of LIBS or Raman/LIBS experiments has already been extensively demonstrated for thin films with thicknesses ranging from 1 µm up to 30 µm, with examples including the analysis of aluminum layers on steel [1], the stratigraphic investigation of paint layers [2] and for polymer-coated metals [3]. The aim of this technical paper is to demonstrate the suitability of the CORALIS instrument for depth profiling of forensic samples. Here we focus on investigation of a car paint sample consisting of several different layers with an overall thickness of 250 µm. Instrument Measurements were done with the CORALIS instrument -- a device capable of performing Raman or LIBS measurements on a single or on a multitude of sampling points. The CORALIS is also capable of acquiring consecutive Raman and LIBS spectra and to do this during d