1. 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 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

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

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

6. 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 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 Power SupplyLaser CCD cameraSpectrometer (Kaiser Optical Systems NXRN model) Computer

9. 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

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

12. 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 AcrylicPolystyrene Hydraulic Ram Calibration Module Probe head

13. 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 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 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

17. Probe head