In situ mobile subaquatic archaeometry evaluated by non-destructive Raman microscopy of gemstones lying under impure waters

David C. Smith

Research output: Contribution to journalConference articlepeer-review

21 Scopus citations

Abstract

A series of laboratory simulations have been made in order to evaluate the credibility of carrying out physico-chemical analysis of cultural heritage items by Raman spectral fingerprinting using a mobile Raman microscope in situ under natural impure water in subaquatic or submarine conditions. Three different kinds of gemstone (zircon, microcline and sodalite) were successively placed under different kinds of impure water into which a low power microscope objective was immersed to eliminate the normal aerial pathway between the objective and the object to be analysed. According to the nature of the impurities (inorganic or organic, dissolved or suspended, transparent or coloured) the results obtained variously gave Raman band intensities stronger than, similar to or weaker than those of spectra obtained without water, i.e. in air. The significant point is that after only minor spectral treatment the less good spectra nevertheless yielded exploitable data with most, if not all, of the key Raman bands being detected. Thus the problems of fluorescence or peak absences under water are of a similar degree of magnitude to the other problems inherent with the Raman spectroscopic technique in aerial conditions, e.g. relative peak intensities varying with crystal orientation; peak positions varying with chemical composition. These results indicate that even if at certain sites of submerged cities or sunken ships, the combination of animal, vegetal, mineral and microbial impurities join together to inhibit or hinder the success of subaquatic or submarine archaeometry, there will certainly be other sites where such activity is indeed credible.

Original languageEnglish
Pages (from-to)2353-2369
Number of pages17
JournalSpectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy
Volume59
Issue number10
DOIs
StatePublished - Aug 2003
Externally publishedYes
EventGEORAMAN 2002 - Prague, Czech Republic
Duration: Jun 12 2002Jun 15 2002

Keywords

  • Impure waters
  • Raman spectroscopy
  • Subaquatic/submarine archaeometry/archaeology

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