1. Project Overview Laser Spectroscopy Group http://laser-spectroscopy.ucc.ie A. A. Ruth Department of Physics, University College Cork, Cork, Ireland

2. (1) Optical trapping of spherical (droplet) particles (12 weeks) (2) Establishment of a small weather station including the operation of a real-time wind shear LiDAR (6 weeks) (3) Differential optical absorption spectroscopy (6 or 12 weeks) (4) Laser induced breakdown spectroscopy (12 weeks) Projects

3. Project 1 Optical trapping of spherical (droplet) particles

4. Physical principle of optical trapping

5. Trap setup Nebulizer Trap chamber & illumination Camera Laser M1M1 M2M2 M3M3 L1L1 L2L2 L3L3 BS BS= beamsplitter 1064 nm

6. Objective lens Beamsplitter Particle chamber Mirror

7. Objectives  Optically trap droplet or transparent spherical solid.  Measure radius of trapped particles.  Study the time the particle can be trapped for as a function of particle size and trapping parameters.  Measure scattering from the droplet/particle and check whether whispering gallery modes were formed.  Compare mode frequencies with expectation based on particle size. Project is for 12 weeks

8. Project 2 Establishment of a small weather station including the operation of a real-time wind shear LiDAR

9. Weather Station Temperature Atmospheric pressure Humidity Precipitation Wind speed Wind direction Standard parameters measured by a weather station: Cup Anemometer

10. LiDAR Principle / Set-up Telescope Receiver Optics Filters Detector (B) Signal Processing Data Acquisition Data Analysis (C) (A) Transmitter (B) Receiver (C) Data Processing (A) Laser Beam Steering Beam Expander Power Measurement

11. (A) Transmitter (C) Data Processing (B) Receiver (A) (B) (C) Aerosol drifting with the wind. Doppler shift of elastically backscattered light used to determine wind speed and direction.

12. Wind (Doppler) LiDAR Objectives Establish weather station. Deploy wind LiDAR. Implement wireless data transmission to a central hub. Analyse and interpret collected data. Collaboration with Civil, Environmental & Energy Engineering Department (Dr. P. Leahy) Project is for 6 weeks

13. Project 3 Differential Optical Absorption Spectroscopy (DOAS) Project 3 Differential Optical Absorption Spectroscopy (DOAS)

14. ...................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................... Established method in trace gas detection: Telescope up to several kilometers Lamp Spectrometer.............................................................................................................................................................................................................................. Experiments in the project will take a little different approach. Long-Path Differential Optical Absorption Spectroscopy (LP-DOAS)

15. Different spectra Steetlights of Cok observd during a merry knight after a kouple of white wine spritzerrrs.

16. Typical spectra of streetlights

17. Xe arc lamps ?

18. Typical spectra of streetlights White LEDs ?

19. Typical spectra of streetlights White LEDs ?

20. Typical spectra of streetlights Low pressure Na lamp?

21. Typical spectra of streetlights High pressure Na lamp?

22. ...................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................... Long path differential optical absorption spectroscopy Telescope street light Spectrometer......................................................................................................................................................................................... aerosol, dust, particulate matter molecular and radical trace species Molecules exhibit structured spectra Aerosol spectra have broad extinction features Intensity I0I0 I aer I aer +I mol Difference spectra are being evaluated !

23. Objectives  Characterize streetlight spectra and select the most appropriate ones for DOAS experiments.  Measure spectra during the entire night and evaluate long term stability of the setup.  Evaluate spectra and check whether (a)retrieval of aerosol extinction is possible, (b)retrieval of molecular absorption is possible, notably of H 2 O or NO 2.  Check feasibility for automized 2D-DOAS study over Cork. Project can be offered as 12 weeks or 6 weeks

24. Project 4 Laser induced breakdown spectroscopy (LIBS)

25. High power laser pulse computer filter spectrometer lensshutter Nd:YAG laser (doubled, 532 nm) oscilloscope (power monitor) CCD fibre vacuum cell Different gases: air, N 2, O 2, Ar Laser Induced Breakdown Exp.

26. 100 ns 400 ns 1000 ns 4000 ns wavelength log (emission intensity) Laser pulse duration typically 10 ns !! Focus typically >10000 K.

27. High power laser pulse computer filter spectrometer lensshutter Nd:YAG laser (doubled, 532 nm) oscilloscope (power monitor) CCD fibre vacuum cell Naphthalene Laser Induced Breakdown Exp.

28. oscilloscope PMT computer filter vacuum cell HR mirror GPIB shutter Nd:YAG laser (doubled, 532 nm) oscilloscope (power monitor) High power laser pulse Laser Induced Breakdown Exp. lens

29. Objectives  Set up LIBS experiment.  Measure “breakdown spectra” of air for different pressures.  Measure “breakdown spectra” of other inert gases, e.g. He, Ar, CO 2.  Trap laser plasma emission in an optical cavity and interpret the results. Project is designed for 12 weeks

32. Light source Detector No sample Conventional absorption spectroscopy d Intensity I 0

33. Absorbance (=optical density) A : ln (I / I 0 ) = d  ( ) = A  = absorption coefficient [cm -1 ], d = sample length [cm] Light source............................................................................................................................................................................................................................................................................................................................................. Detector Absorbing sample (e.g. Gas) Conventional absorption spectroscopy d Intensity I