Mineralogy

The chemistry of rocks composing the surface of the earth is complex. Therefore, geologists and mineralogists need powerful characterization techniques to get the detailed information for exploration purposes and to study the rock formation processes and history. Rocks typically consist of aggregates of one or several minerals. Each mineral can be defined by its crystalline structure and chemical composition. Raman spectroscopy can offer more information for both of these features.

TimeGated® represents one of the latest advances in Raman technology. Below are some of the benefits provided:

  • It enables significant or even total luminescence rejection from a Raman measurement
  • It simultaneously yields the time-resolved fluorescence spectrum
  • The different decay times of luminescence centers (such as rare earth metals and transition metals) make time-resolved spectroscopy very effective technique to study these materials

Example of Timegated® results in mineralogy

Dolomite Raman spectra between 700 and 1150 cm-1 measured with Timegated (TG) Raman 532 spectrometer and traditional (CW) Raman spectrometer. TG spectrum shows clear double peaks for both asymmetric bending mode around 720 and symmetric stretching mode around 1095 while CW Raman shows only single peaks. This can be interpreted so that TG Raman spectrometer separates calcite and magnesite based vibrations from each other, due to some nonlinear mechanism activated by the high instantaneous power of the pulsed excitation.

Gemmology

Many minerals, in original form or considered as gemstones, have unique Raman spectra. That spectra can be used to verify that a stone has been identified correctly. As most gemstones are natural materials created in a very complex environment, spectral variations related to the chemical and structural differences are expected. Yet the major peaks of gemstone spectra are quite consistent.

The Raman spectrometer is routinely used for the detection of emerald fillers, HPHT treatment of diamonds, analysis of the nature of a gemstone, analysis of gemstone inclusions and treatments, and the characterisation of natural or colour enhanced pearls and corals.

Example of Timegated® results in gemmology

Below you can see some measurements made by Timegated® with some comparison to equivalent CW Raman and without.