Raman spectroscopy dating
Spectroscopic examination is the only method that allows conservators and art historians to precisely identify the materials artists used for their works. This information enables art historians and scholars to understand what artistic materials were available during a certain period in a particular region, and therefore illuminates trade routes and interactions among cultures. Spectroscopy may also help uncover the manufacturing methods used to fabricate artistic materials, providing valuable data about the development of technical skills over time. Spectroscopy also enables scholars to date objects. Because some materials were available in particular regions and periods, the retrieval of pigments with a well-known date of invention allows art historians to date artifacts post quem. Spectroscopy is also extremely useful to fight forgery.
Towards Fingermark Dating: A Raman Spectroscopy Proof‐of‐Concept Study
The internat Radiocarbon dating of ivory requires destructive sampling on a scale not always compatible with the requirements of the preservation and curation of cultural objects. The development of a minimally-destructive dating technique is urgently needed. Raman spectroscopy can detect the changes in the organic and inorganic molecular components of ivory that occur with time.
It has been suggested that these vibrational spectroscopic changes could be used to assess the relative date of mammoth ivories, assuming that the state of preservation of the ivory is directly related to its age. This paper tests this assumption with specimens of mammoth ivory of known date and burial environment and concludes that the vibrational spectra of ivory cannot in general be used to deduce the age of the specimen.
The age of the raw materials of these objects, although not necessarily the date at which they were worked, can be gained through AMS 14 C dating. In many cases, destructive sampling on the scale required is incompatible with the requirements of the preservation and curation of the object. The development of a minimally-destructive dating technique has therefore been sought with some urgency.
XRD, Rietveld method, and FTIR spectroscopy both detected an increase in the size, particularly the length, of the bioapatite carbonated hydroxyapatite crystals with increased weathering. In addition, FTIR spectroscopy detected degradation of the collagen component and changes in chemical composition of the bioapatite in direct correlation with the increase in size of the crystallite.
Assuming that the least weathered samples were the youngest and that weathering increased with increasing age, this led Banerjee et al. As a direct result of that publication, the possibility that FTIR spectroscopy could be used to date ivories quickly gained currency in the museum world, as it seemed to offer a less destructive alternative to radiocarbon dating. A dating technique based on preservation parameters would certainly not be capable of producing absolute dates as the rate of these changes are largely dependant on variables such as the thermal history of the object, the degree of sub-aerial weathering undergone and the nature of the burial environment.
It is well understood that different burial conditions affect the rate and trajectory of the bone diagenesis Smith et al. Edwards et al. As a technique for relative dating it would also, therefore, be unlikely to produce meaningful results for ivories with different biographies i. However, Bannerjee et al. Their results do show a direct correlation between these changes and the visible degree of weathering defined as A: Yellow and slightly weathered and C: We therefore set out to test the hypothesis that weathering in ivory is correlated with age, using Raman spectroscopy and ivory samples of broadly similar date from a single site.
To gain a quality spectrum requires either the preparation of a flat surface on the specimen or for a sample of the specimen to be powdered. In addition, FTIR spectroscopy is very sensitive to water content and specimens effectively need to be dehydrated to the same extent to gain good quality spectra for comparison. Sampling of cultural objects is not always curatorially acceptable and even if surface preparation of a discrete area is considered feasible, dehydration of the ivory object would carry a very high risk of catastrophic physical damage.
These problems led the authors to consider alternative analytical techniques and Raman spectroscopy was selected as a substitute for FTIR spectroscopy for this experimental work. It allows the same changes in microstructure and molecular chemistry to be observed in ivory but good quality spectra are gained without the need for dehydration or surface preparation, beyond brushing off obscuring sediments.
Raman spectroscopy also allows comparison to be made over a wider range of wavenumbers, and provides a greater potential to identify the chemical species. Whereas FTIR spectroscopy has a logarithmic dependence between absorption intensity and concentration, Raman spectroscopy has a linear dependence between the concentration of the species under investigation and the irradiance.
This allows the changes in specific components in different specimens to be roughly estimated directly from the spectra. The spectra were recorded at 4 cm -1 resolution and scans accumulation. This equipment accommodates large sample diversity in terms of size, curvature and irregularity of surface. All the fragments were dry and had been stored at the same ambient RH. Three spectra were collected from each of two surfaces of all the ivory specimens.
Figure 1: Two permafrost-preserved mammoth ivory off-cuts of unknown provenance. Figure 2: The mammoths were mostly males and several complete tusks, and 32 plastic sacks of ivory fragments, were recovered. Material from this site was conserved at the University of Bradford, Archaeological Sciences conservation laboratory. A small quantity of the fragmented ivory was retained, untreated, for future research studies: The lowermost and uppermost levels of this channel contained sands and gravels deposited by relatively fast flowing water.
Between these were the organic silts and sands, bone and ivory, plant and insect remains, which seem to have accumulated at a time when the channel had become a meander, cut off from the main water flow. Optically-stimulated luminescence OSL dating of these organic sediments places their deposition at the transition between Marine Isotope Stages MIS 4 and 3, approximately ka Gamble, in press. This had produced substantial variation in the colouration and state of preservation of the bone and ivory material Figure 2.
That in the sands and gravel was greatly fragmented and friable and could be rusty red in colour. One tusk in particular, at the interface between these deposits, showed a range of variation in both colour and condition along its length. The ivory specimens analysed from Lynford were especially selected to represent the full range of preservation in these palaeochannel deposits. Figures 3 and 4. The spectrum of permafrost specimen 2 Figure 3 showed that both the collagen and the bioapatite were well preserved and looked very similar to spectra of modern elephant ivory Brody et al.
Figure 3: Raman spectrum of ivory specimen permafrost 2. Figure 4: Stacked plot of Raman spectra of ivory specimens permafrost 1 and 2 and Lyford 2 white side. Spectra normalised on the phosphate band cm -1 Figure 4: Although the bioapatite is similarly preserved in both specimens, the collagen is significantly reduced in specimen1and in the wavenumber region around wavenumber cm -1 , the peaks show a smearing or broadening, indicating an increase in the characteristic degradation products of collagen.
Interestingly the best waterlogged-preserved ivory from Lynford, Lynford 2, has produced a very similar spectrum to permafrost 2 suggesting that the diagenetic changes that have occurred are very similar Figure 4. In contrast to Lynford 2, the peak at ca. Figure 5: Stacked plot of Raman spectra from Lynford ivory specimens 1 to 4. Spectra normalised on the phosphate band cm From these spectra alone, it would not be possible to distinguish between the mammoth ivory specimens Lynford 1, 3 and 4.
The spectra obtained from the upper and lower surfaces are very much the same, when considering the inorganic matrix, but the residual organic signal from the lower surface is swamped by contamination from the burial environment Figure 6. Figure 6: Raman spectra from the upper and lower surfaces of ivory specimen Lyford 1. The upper surface of the specimen is stained beige by the burial environment but the lower surface, where the split occurred, is white. When comparing these two surfaces the spectra are very different Figure 7.
Figure 7: Raman spectra from the upper and lower white surfaces of ivory specimen Lyford 2. Contamination of surfaces exposed to the burial sediments could have been reduced by sample preparation, as is done for FTIR spectroscopy, but even then it cannot be suggested that the results obtained could have been used in dating with any greater confidence. The similarities in the results only indicate that they are probably of the same commercial grade of ivory.
However if the assumption that the state of preservation of the ivory and its age are directly linked is valid, the weathered areas of sample 1 would have to be very much older than the ivory exposed on its cut surfaces. Sampling deep within the core of cultural objects, to avoid the more weathered exterior, could be very problematic. The wide variability in the preservation of the organic and inorganic components of the ivory clearly show that many factors, other than the time elapsed from the death of the mammoth, contributed to the state of preservation of the ivory.
Any assessment of age based on the Lynford samples would conclude that they represent material of a wide range of age, which would, of course, be quite misleading. This study confirms that the preservation of ivory from a single site and even across the surface of a single object may vary too much to allow even an approximate relative chronology to be obtained. Results published previously, that appear to show the contrary, would appear to be the product of small sample numbers and coincidental correlation for which there was no true cause and effect relationship.
FTIR and Raman spectroscopy can detect and quantify changes that occur in ivory as it weathers but these changes cannot be used as an indication of the relative age of ivories. We also thank the University of Bradford for their support in this project. Banerjee, A. Bortolaso, ed. Ivory and Species Conservation: Boismier, W. Interim statement.
Proceedings of the Prehistoric Society , Brody, R. Analytica Chimica Acta , Edwards, H. Analytical and Bioanalytical Chemistry , Gamble C. Excavations at Lynford Quarry , Norfolk. English Heritage, London. Smith, C. Journal of Archaeological Science , Nielsen-Marsh, C. The international Arboco workshop towards a better understanding and preservation of ancient bone materials. Edwards et Esam Ali. Plan 1. Selection of ivory specimens for analysis. Introduction 1 The dating of bone and ivory objects is fundamental to their authentication, to the development of archaeological and historical typographies, and to the detection of the trafficking of CITES protected materials.
Selection of analytical technique 5 FTIR spectroscopy is a relatively destructive technique.
The Fourier transform Raman vibrational spectra of five ancient molar teeth ( burial periods ranging from to about years ago) were analysed in. based on two molecular spectroscopy techniques, that is FT-IR and FT-Raman. A set of samples dating from about B.C. until present has been examined in.
Raman spectroscopy is an optical technique that measures the chemical composition and molecular structure of a sample. The application of Raman spectroscopy and microscopy within biology is rapidly increasing and it has proven to be a valuable analytical tool for various applications. As the use of Raman in the laboratory and clinical setting increases there will be a need to better characterise and standardise protocols to facilitate use in clinical settings.
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Towards Fingermark Dating: A Raman Spectroscopy Proof‐of‐Concept Study
Forensic document examiners in the Department of Justice have identified specific needs in the analysis of intersecting lines with respect to sequence and dating of lines in questioned documents such as forgeries and alterations. Raman spectroscopy has great potential in forensics, in part because it is nondestructive to evidence. Raman has recently shown promise in successfully identifying and differentiating several different types of inks. There is, however, a shortfall in the ability to time-sequence marks, and to identify specific inks and pigments, especially in the case of intersecting lines. To date, this has received little attention. One major problem is the fluorescence of paper fibers and inks which masks valuable spectral information that identifies the inks.
Towards Fingermark Dating: A Raman Spectroscopy Proof‐of‐Concept Study
As a service to our authors and readers, this journal provides supporting information supplied by the authors. Technical support issues arising from supporting information other than missing files should be addressed to the authors. Raman spectroscopy is, herein, evaluated for the purpose of estimating the age of fingermarks deposits. It is hypothesized that fibrous proteins are present and that oxidation of amino acid side chains can be observed both through Raman and fluorescence spectroscopy. In parallel, new and ongoing advances in forensic analysis have been realized, which provide additional information to the forensic investigator, 1 for example chemical identification of contaminant particles, 2 age estimation of FMs 3 and blood stains, 1c and gender determination based on saliva 4 and blood. Large challenges are expected for the development of such a FM age determination method, mainly owing to the large amount of variables influencing the kinetics involved in FM degradation. Moreover, they often encompass hyperspectral imaging, that is, the image contrast is governed by spectral information from each pixel. Likely, the chemical composition of the oily regions is represented by sebaceous secretions, whereas the solid particulates mainly originate from the epidermis. Raman spectra from a freshly deposited FM red and after one month of aging blue. Measurements obtained from a particulate deposit.
Stable isotope analyses for paleodiet investigations require good preservation of bone protein, the collagen, to obtain reliable stable isotope values.
Palenik, C. Pigments are encountered in a variety of trace evidence, including automotive paints, architectural paints, inks, fibers, and other polymers. Limitations inherent to each of these techniques have limited the practicality of pigment identification in the analysis of trace evidence.
Time and Location: Raman spectroscopy is now widely used to detect and identify chemicals, biological materials and drugs. Multi-wavelength Raman spectroscopy, sometimes referred to as hyper-Raman, is a unique enhancement of this technique and is particularly effective in the detection of a particular substance within a complex mixture, i. The development of this technique at the Naval Research Laboratory will be outlined and applications of this approach presented. The analysis techniques, derived from hyper-spectral imaging, will be discussed. Charles Manka received an A. His Ph. Utilizing a gift of a high powered laser from Texas Instruments, he began research in Laser Produced Plasmas and associated diagnostics. This group has utilized much lower powered, but frequency agile lasers, to detect explosives, bio- and chemical hazards. He continues his association with this group after official retirement in
Olivier Bonnerot. What information can Raman spectroscopy provide about pure and mixed carbon inks? Two main types of inks coexisted in Early Medieval times: Many variations within these types existed, depending on the source of raw materials and their proportion. In addition to these, an intermediate mixed type of ink, with both iron and carbon as colouring agents, was sometimes used, especially in early Arab manuscripts. The first one aims at comparing the spectra of different carbon inks from Antiquity to the Middle Ages with Raman spectroscopy, while the second one focuses on the identification and comparison of mixed inks.
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Authentication using the Infrared Laser Raman Spectrograph A fake is a point that has been represented as ancient to defraud a buyer; and, many criminals go to extreme lengths to make their modern points look old. Fakes can be found at every level of collecting. Some sell at flea markets for three dollars, and some have sold for tens of thousands of dollars. Millions of modern points are made each year in the US, and an unacceptable number are passed off as authentic relics. This flood of bogus material has reduced the value of authentic pieces and skewed the archaeological record.
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Сьюзан казалось, что она сходит с ума. Она уже готова была выскочить из комнаты, когда Стратмор наконец повернул рубильник и вырубил электропитание. В одно мгновение в шифровалке установилась полная тишина. Сирены захлебнулись, мониторы Третьего узла погасли. Тело Грега Хейла растворилось в темноте, и Сьюзан, инстинктивно поджав ноги, прикрылась пиджаком Стратмора.Raman Spectroscopy - 1 ( Basic Principle)