1. 1 Naama Lang-Yona, Ali Abo Riziq, Yinon Rudich Department of Environmental Science and Energy Research Weizmann Institute of Science Aerosol Complex Refractive Index Retrieved by a New Continuous Wave-Cavity Ring Down-Aerosol spectrometer

2. 2 From the IPCC report, 2007 Large uncertainty!

3. 3 Aerosols solid particles or liquid droplets that are suspended in a gas

4. 4 Characterization of SOA, from biogenic emission can hence lead to a better understanding of these feedbacks (Kulmala et. al, 2004). T STRESS - ? VOC+OH/O3/NOxSOA VOC + OH/O3/NOx SOA SOA

5. 5 Developing a technique, by which we can measure the optical properties of SOA. Requirements: Portable system Highly sensitive Fast measurements Objectives Continues Wave-Cavity Ring Down- Aerosol Spectrometer (CW-CRD-AS)

6. 66 Principles of Cavity Ring Down (CRD) Laser (PMT) Laser (PMT)

7. 7 Mie fit Absorption Scattering Mie fit Complex refractive index Refractive Index Refractive Index -How much the speed of light (or other waves ) is reduced inside the medium

8. 8 CW-CRD setup 90 x 150cm

9. 9 Validation The results show that the Mie fit successfully retrieves the refractive index of different absorbing and scattering aerosols. PSL (Polystyrene latex sphere) Suwannee River Fulvic Acid Nigrosin Ammonium Sulphate

10. 10 Stability

11. 11 Accuracy σ ext calculatedσ ext measured (3.82  0.01)×10 -9 cm 2 (3.75  0.01)×10 -9 cm 2 2% Error

12. 12 Characterization of SOA, from biogenic emission can hence lead to a better understanding of these feedbacks (Kulmala et. al, 2004). T STRESS - ? VOC+OH/O3/NOxSOA VOC + OH/O3/NOx SOA SOA

13. 13 SOA to CRD VOC JPAC chambers in Jülich, Germany PortableCW-CRDsystem Plantchamber Reactionchamber

14. 14 Preliminary results, summer 2008 No absorption in the visible wavelength Emissions from Mediterranean Oak – oxidation with O 3 /OH In the JPAC chambers in Jülich, Germany.

15. 15 Conclusions Accuracy –Single mode CW laser single exponential decay High repetition rate – Sampling rate of 400Hz (higher repetition rate is achievable). Reliability – Good agreement between measured RI for different types of aerosol and previous measurements conducted with Pulsed-CRD and other optical systems. The new system is stable and consistent for long measurement and with varying particle concentrations. Suitable for field measurements - High qualities, small dimensions and low power requirements.

16. 16 Further Developments Planned in the Future Addition of UV laser to the current VIS 532nm laser. Coupling the system to photo acoustic cell, in order to measure extinction and absorption simultaneously.

17. 17 Thank you!!