Second Generation Laser Raman Spectrometer for Deep Ocean Analysis

1. Second Generation Laser Raman Spectrometer for the Deep Ocean Second Generation Laser Raman Spectrometer for the Deep Ocean Alana Sherman 1 , Rachel M. Dunk 1 , Sheri N. White 2 , William Kirkwood 1 , Edward T. Peltzer 1 , Peter Walz 1 , Farley Shane 1 , Richard Henthorn 1 , Karen A. Salamy 1 , Peter G. Brewer 1 1 Monterey Bay Aquarium Research Institute, Moss Landing, CA 2 Woods Hole Oceanographic Institution, Woods Hole, MA

2. Raman Spectroscopy Raman Spectroscopy • Vibrational spectroscopy – Based on Raman scattering • The inelastic scattering of monochromatic radiation – The shift in energy of the scattered light is equal to the change in the vibrational energy of the molecule – The Raman spectrum serves as a fingerprint of a substance based on molecular composition and local environment • Vibrational spectroscopy – Based on Raman scattering • The inelastic scattering of monochromatic radiation – The shift in energy of the scattered light is equal to the change in the vibrational energy of the molecule – The Raman spectrum serves as a fingerprint of a substance based on molecular composition and local environment

3. • The technique provides the ability to make in situ geochemical measurements in the deep ocean. • Advantages of Raman Spectroscopy: – Can analyze solids, liquids and gases – Rapid analysis – Can perform in situ analysis targets with stability zones confined to the deep ocean – Generally non-destructive, and requires little or no sample preparation • The technique provides the ability to make in situ geochemical measurements in the deep ocean. • Advantages of Raman Spectroscopy: – Can analyze solids, liquids and gases – Rapid analysis – Can perform in situ analysis targets with stability zones confined to the deep ocean – Generally non-destructive, and requires little or no sample preparation Raman Spectroscopy in the Ocean Raman Spectroscopy in the Ocean

4. • A number of oceanic targets are Raman active: – Gases • CO 2 , CH 4 , N 2 , O 2 , H 2 S, etc. – Minerals • Sulfides, anhydrite, calcium carbonates, silicates, feldspars, magnetite, etc. – CO 2 and CH 4 hydrates • A number of oceanic targets are Raman active: – Gases • CO 2 , CH 4 , N 2 , O 2 , H 2 S, etc. – Minerals • Sulfides, anhydrite, calcium carbonates, silicates, feldspars, magnetite, etc. – CO 2 and CH 4 hydrates Raman Spectroscopy in the Ocean Raman Spectroscopy in the Ocean

5. 1 2 3 1 2 3 DORISS 1 Deep Ocean Raman In Situ Spectrometer DORISS 1 Deep Ocean Raman In Situ Spectrometer 40” 10” 20” 12” 15” 6”

6. Operations Operations ROV deployed instrument • The instrument housing is mounted in the rear drawer of the ROV • The probe head is carried in front of the ROV • Communications between Doriss and shipboard computer via Ethernet • Spectra of targets, video, and environmental data are transmitted back to the operator Doriss2 Probe head Spectrum Raman Shift (cm -1 ) Intensity (Counts)

7. DORISS1 DORISS1 • Scientific Successes – First deep ocean Raman spectra – 3 years of successful deployments – Collected data from hydrothermal vents at Gorda Ridge, natural hydrates from Hydrate Ridge – Demonstrated worth of technique – 8 papers published • Scientific Successes – First deep ocean Raman spectra – 3 years of successful deployments – Collected data from hydrothermal vents at Gorda Ridge, natural hydrates from Hydrate Ridge – Demonstrated worth of technique – 8 papers published • Technical Challenges – Prototype instrument not suitable for routine expeditionary use • Weight and size • Sensitivity • Reliability and robustness

8. DORISS2 DORISS2 Power Supply Laser CCD camera Spectrometer (Kaiser Optical Systems NXRN model) Computer

9. DORISS2 DORISS2 • Improvements: – U-shaped spectrometer simplifies housings – 90 lbs lighter than DORISS1 • Can be deployed on vehicles with limited payload – Increased sensitivity, due to new back illuminated CCD camera – More robust and reliable • Improvements: – U-shaped spectrometer simplifies housings – 90 lbs lighter than DORISS1 • Can be deployed on vehicles with limited payload – Increased sensitivity, due to new back illuminated CCD camera – More robust and reliable 12” diameter, 30” long

10. DORISS2 Data CH 4 -H 2 S Fractionation DORISS2 Data CH 4 -H 2 S Fractionation

11. CH 4 -H 2 S Fractionation CH 4 -H 2 S Fractionation Disappearance of the 2610 Δ cm -1 H 2 S peak with time.

12. In Situ Calibration In Situ Calibration • Would like a way to calibrate intensity and wavelength of the instrument in situ . • Calibration module experiments: – Relative intensity correction standard: NIST SRM 2242 luminescent glass – Wavelength correction: Acrylic and Polystyrene • Would like a way to calibrate intensity and wavelength of the instrument in situ . • Calibration module experiments: – Relative intensity correction standard: NIST SRM 2242 luminescent glass – Wavelength correction: Acrylic and Polystyrene NIST SRM2242 Acrylic Polystyrene Hydraulic Ram Calibration Module Probe head

13. Calibration Data Calibration Data • Less than 2% error between white light corrected and SRM 2242 corrected spectra • Difficulty extracting water signal when using stand-off optic • Less than 2% error between white light corrected and SRM 2242 corrected spectra • Difficulty extracting water signal when using stand-off optic Comparison of White Light corrected and SRM 2242 corrected Acrylic spectra SRM2242 Corrected WL Corrected Intensity (Normalized) Raman Shift (cm -1 )

14. Future Developments Future Developments • Improve fiber optic cables • Integrate new smaller probe head • Smaller positioner • Improve fiber optic cables • Integrate new smaller probe head • Smaller positioner Kaiser Optical Systems, MultiRxn Probe

15. Acknowledgements Acknowledgements • Crew of the R/V Western Flyer and R/V Point Lobos • Pilots of the ROV Tiburon and ROV Ventana • Technical support of John Ferreira, Larry Bird, Jim Scholfield, Cheri Everlove • Kaiser Optical Systems • Steve Choquette at NIST • David & Lucile Packard Foundation • Crew of the R/V Western Flyer and R/V Point Lobos • Pilots of the ROV Tiburon and ROV Ventana • Technical support of John Ferreira, Larry Bird, Jim Scholfield, Cheri Everlove • Kaiser Optical Systems • Steve Choquette at NIST • David & Lucile Packard Foundation

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17. Probe head

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