The determination of the content of graphitic carbon (GC) in atmospheric aerosol samples deposited on glass fiber filters (Pallflex E70-2075W) is accomplished by means of a new Raman spectroscopic method. Raman spectra of atmospheric GC contain two main bands located at about 1600 and 1300cm−1. The GC mass loading of the filter samples is obtained by integrating the band at 1600cm−1, which scales with the amount of graphitic structures. The method is calibrated with the carbon black Monarch 71 (M71), because the location and shape of the Raman bands of M71 and atmospheric GC are very similar. Due to the specific sensitivity of the Raman method for GC a high precision of 2% is achieved (detection limit of 0.08μgcm−2). The special filter type was chosen for the Raman method, because it is employed inside the particle soot absorption photometer (PSAP), which measures the particle absorption coefficient σap by a change in light transmission during aerosol collection. This offers the opportunity to relate σap to the subsequent Raman measurement of the GC mass concentration, mGC, on one and the same aerosol sample in order to determine the GC mass absorption efficiency δGC. In a first attempt this approach is applied to atmospheric aerosol particle measurements carried out on a mountain site in central Germany yielding δGC values between 10 and 18m2g−1 with an average of (14.7±2.8)m2g−1. These results are interpreted by published model calculations where mass absorption efficiencies of light absorbing carbon inside internally mixed particles are computed. From the comparison it can be concluded that GC constitutes the dominant part of light absorbing carbon and is mainly located in the accumulation mode of aged continental aerosol particles prevailing at the observational site.

An intensive soot aerosol characterisation campaign was organised in October 1999 at the large aerosol chamber facility AIDA in Karlsruhe, with the participation of scientists from nine Austrian, German, Russian, and Swiss Research Centres and Universities who contributed special equipment and expertise. The main goal was a comprehensive physical and chemical characterisation of soot aerosol from a modern turbo Diesel passenger car equipped with an oxidation catalyst, in comparison with artificial soot aerosol (“Palas” soot) from a commercial spark discharge generator which is often used as a surrogate for combustion soot in laboratory studies. Included were experiments with pure ammonium sulphate aerosol as well as its external mixtures with soot aerosols, and their evolution to partially internal mixtures on time scales up to 45h. Effects of organic coatings on various aerosol properties, generated in situ by heterogeneous nucleation of products from the reaction of α-pinene with ozone were also investigated. The purpose of this paper is to present an overview of the whole campaign. This includes the description of technical and modelling tools, standard procedures, and the presentation of experimental parameters in tabular form, as a common background for a series of companion papers which focus on selected scientific issues. Included is a comparison between Diesel and spark generated soot in terms of their Raman and ESR spectra. The most remarkable difference is the large spin density in spark generated soot, which exceeds that of Diesel soot by an order of magnitude. However, the spin densities in both materials are too small to affect the surface properties of soot aerosols to a significant extent.

Analyses of biomaterial by ‘classical’ Raman spectroscopy with excitation in the visible range has not been possible since the fluorescence of many essential constituents of all animal and plant cells and tissues overlays the Raman spectra completely. Fluorescence, however, is virtually avoided, when Raman spectra are excited with the Nd:YAG laser line at 1064nm. Within seven dissertations we explored different fields of potential applications to medical diagnostics. Identification and qualification of tissues and cells is possible. Tumors show small but significant differences to normal tissues; in order to develop a reliable tool for tumor diagnostics more research is necessary, especially a collection of reference spectra in a data bank is needed. Raman spectra of biomineralization structures in teeth and bones show pathological tissues as well as the development of new mineralized structures. NIR Raman spectra of flowers, leaves, and fruit show, without special preparation, their constituents: alkaloids, the essential oils, natural dyes, flavors, spices and drugs. They allow application to taxonomy, optimizing plant breeding and control of food.

A quantitative determination of the mineralization of bone tissue and of the hydroxyapatite (HA) content of HA coatings following total hip arthroplasties in dogs was performed using an optimised FT Raman microscope (inverted microscope, high throughput of radiation) that allows minimal sample preparation without fluorescence. The lateral resolution reached down to 10 mu m. A similar cross-sectional course of the HA content - reaching from the implant body to the ongrown bone - was found in all cases. In the immediate vicinity of the prosthesis a large HA content could be observed that decreased to a minimum towards the periphery of the coating and increased at the site of the ongrown bone. For the interface between bone and HA coating a transitional zone was observed at a lateral distance of 30-40 mu m to the implant. Bone ingrown into the gap between detached HA coating and implant had a lower HA content than bone ongrown onto the coating peripherally. Thus, Raman microscopy can determine the relative age of bone tissue at different sites in the course of implant integration.

During combustion soot goes through different molecular structures. The Raman spectra of flame soot, collected in premixed flames at different flame heights and flame temperatures, were analysed in regard to their structural properties and in comparison with those of disordered graphite. Besides the G- and D-band of disordered graphite, a third Raman band at approximately 1188 cm-1 was observed which was tentatively assigned to mixed s–s bondings or to the C–C and C2C stretching vibration modes of polyene-like structures. The G-band position, the D-band width, and ID/IG intensity ratio describe the graphitic order in the particles. According to this result the graphitic order of the untreated soot particles decreases with decreasing flame temperature and flame height, whereas the size La of the graphitic sheets is nearly constant.

An optimized FT Raman microscope (inverted microscope with high throughput of radiation) was developed that allows minimal sample preparation and Raman spectroscopy without fluorescence. A quantitative determination of the mineralization of bone tissue and hydroxyapatite (HA) coatings of hip and knee prostheses was performed. The lateral resolution reached down to 10 microm. The distribution of the HA content in the coatings investigated was found to be similar all the time. This result was independent of the composition of the coatings and the history of the whole prosthesis. In the immediate vicinity of the prosthesis a large HA content could be observed that decreased to a minimum towards the periphery of the coating and increased at the site of the ongrown bone. For the interface between bone and HA coating a transitional zone was observed at a lateral distance of 30-40 microm to the implant.

NIR-FT-Raman spectroscopy is the most suitable tool for investigation of biological samples, because the fluorescence of organic substances is reduced to a minimum. To examine the applicability of NIR excited FT-Raman spectroscopy to the study of cell cultures and tissues, measurements were made with an inverted Raman microscope, a modified Zeiss Axiovert 135. This system allows the collection of Raman spectra both by Koehler laser illumination and the confocal principle:Koehler laser illumination avoids overheating and denaturation of the sample because the exciting laser beam illuminates the sample as an unfocused collimated beam. An integrative collection over the whole image of the microscope objective is necessary to increase the Raman light flux.The confocal arrangement allows high spatial resolution which is reached by selective collection of the Raman scattering of details of the sample. A larger spatial resolution leads to a decreased light flux of the Raman scattering, this is compensated by a focused laser beam.We have used NIR-FT-Raman spectroscopy to investigate the spectra of normal breast tissues, potentially useful in the diagnosis of cancer. (C) 1997 Elsevier Science B.V.

Raman spectroscopy may aid the development of new tools to make medical diagnostics more objective. By shifting the exciting radiation of Raman spectrometers from the visible to the NIR region, the competing fluorescence of normal cell components can be reduced. The fluorescence of organic molecules is virtually eliminated when excitation by the Nd: YAG laser radiation at 1064 nm is employed. In combination with optimized interferometers and remote probes, it is now possible to record Raman spectra in vivo in acceptable times. Software programs are developed which interpret the spectra to help in the identification of suspicious tissues and micro-organisms, and for establishing medical diagnosis. In each case, the information distributed over the whole spectrum has to be evaluated.