Project Overview Laser Spectroscopy Group laser-spectroscopy.ucc.ie

1. Project OverviewLaser Spectroscopy Grouphttp://laser-spectroscopy.ucc.ie A. A. Ruth Department of Physics, University College Cork, Cork, Ireland

2. Projects (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)

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

4. Physical principle of optical trapping

5. Trap setup Laser Nebulizer M2 1064 nm L1 M1 Trap chamber & illumination L2 BS L3 M3 Camera BS= beamsplitter

6. Particle chamber Objective lens Beamsplitter 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 2Establishment of a small weather station including the operation of a real-time wind shear LiDAR

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

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

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

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

13. Project 3 Differential Optical Absorption Spectroscopy (DOAS)

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

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

16. Typical spectra of streetlights

17. Typical spectra of streetlights 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 aerosol, dust, particulate matter Telescope molecular and radical trace species Spectrometer street light Molecules exhibit structured spectra Aerosol spectra have broad extinction features I0 Iaer Iaer+Imol Intensity Difference spectra are being evaluated ! l

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 • retrieval of aerosol extinction is possible, • retrieval of molecular absorption is possible, notably of H2O or NO2. •  Check feasibility for automized 2D-DOAS study over Cork. Project can be offered as 12 weeks or 6 weeks

24. Project 4Laser induced breakdown spectroscopy(LIBS)

25. Laser Induced Breakdown Exp. Nd:YAG laser (doubled, 532 nm) oscilloscope (power monitor) High power laser pulse Different gases: air, N2, O2, Ar shutter lens vacuum cell filter fibre CCD computer spectrometer

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

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

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

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, CO2. • Trap laser plasma emission in an optical cavity and • interpret the results. Project is designed for 12 weeks

32. Conventional absorption spectroscopy No sample Light source Detector IntensityI0 d

33. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Conventional absorption spectroscopy Absorbing sample (e.g. Gas) Light source Detector IntensityI d Absorbance (=optical density) A: ln(I / I0) =d () = A  = absorption coefficient [cm-1], d = sample length [cm]