Raman up and running at the South Australia Drill Core Reference Library.
The eagerly awaited new Metrohm i-Raman Ex spectroscopy instrument has arrived. It is additional to the long-standing HyLoggerTM 3. Raman is a spectroscopic technique that measures the change in energy of scattered light which occurs at about 1 in 10 million photons. HyLogger 3 measures reflectance and absorption in the 380–2,500 nm and 6,000–14,500 nm wavelength range. Both techniques have advantages and limitations and are complementary.
The instruments will be run in parallel as part of the Geological Survey of South Australia’s ongoing spectral scanning of drill core and drill chip materials. Over 3,700 m of drill core and drill chips have already been scanned this year using the HyLogger 3. The samples include a range of areas across the state from co-funded drilling (PACE) to the much-awaited MinEX CRC Delamerian National Drilling Initiative.
Results from the Raman will be added to the Spectral Geologist datasets as an independent mineral identification and quantification tool.
The benefits of using Raman spectroscopy are:
- non-destructive
- unambiguous mineral discrimination
- polymorph differentiation
- mineral phase identification
- accurate spectra
- spectral library generation
- no sample preparation
- efficient and easy to use in real time
- portable so can take into the field
- solids, liquids or gases, glass vials, and aqueous solutions and wet samples can be used.
The Raman instrument filters out elastic scattered light (Rayleigh) and captures in-elastic scattered light (Raman). Raman scattering, or the Raman effect, was discovered in 1928. The in-elasticity refers to the variation in energy from the original incident light that experiences a change in wavelength after it interacts with molecules.
The Metrohm i-Raman Ex model uses a near infrared 1064 nm monochromatic laser as the source of light to excite the molecules. In microscope mode it can be focused down to 21 µm for detailed mineralogical analysis of fine-grained materials.
Metrohm’s Dr Siva Arumugam (far right) training Geological Survey of South Australia staff (L–R: Alicia Caruso, Adrian Fabris, Doug Mowbray, Georgina Gordon) on use of the new Raman spectroscopy instrument (located on the far left of the table).
To view and download the latest spectral geoscience data visit either:
– Georgina Gordon and Doug Mowbray, March 2022
