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COST Action 529, Mierlo, 31.03.06-2.04.06 G.Revalde, ASI Light related activities at High resolution and light source technology laboratory, Institute.

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Presentation on theme: "COST Action 529, Mierlo, 31.03.06-2.04.06 G.Revalde, ASI Light related activities at High resolution and light source technology laboratory, Institute."— Presentation transcript:

1 COST Action 529, Mierlo, G.Revalde, ASI Light related activities at High resolution and light source technology laboratory, Institute of Atomic Physics and Spectroscopy, Riga

2 COST Action 529, Mierlo, G.Revalde, ASI Institute of Atomic Physics and Spectroscopy

3 COST Action 529, Mierlo, G.Revalde, ASI Laboratory is a part of the Institute of Atomic Physics and Spectroscopy Members Dr. Atis Skudra (head) Dr. Imants Bersons Dr. Gita Rēvalde Eng. Juris Siliņš PhD students: Nataļja Zorina, Egils Bogans, Zanda Gavare, Mr. Mārtiņš Bērziņš Collaboration partners: Institute of Theoretical and Applied Mechanics, Novosibirsk, Russia Institute of Theoretical and Applied Mechanics, Novosibirsk, Russia CPAT, Toulouse, France CPAT, Toulouse, France Institute of Non-thermal plasma physics, Greifswald, Germany Institute of Non-thermal plasma physics, Greifswald, Germany University of St.Petersburg, Russia University of St.Petersburg, Russia Tomsk State University, Russia Tomsk State University, Russia University of Mainz, Germany University of Mainz, Germany Moscow Kurchatov’s Institute, Russia Moscow Kurchatov’s Institute, Russia

4 COST Action 529, Mierlo, G.Revalde, ASI Research fields Low-pressure discharge plasma studies, mainly, inductive/capacitatively coupled; High frequency electrodeless discharge lamp technology and manufacturing Plasma/wall interaction Working life studies Radiation stability High-resolution emission spectroscopy, time and spatially resolved Spectral line shapes (resolution approx cm -1 ) (VUV-IR) Spectral line intensities - absolute and relative (VUV-IR) in dependence on working conditions, pressure etc Ion trap spectroscopy Atomic absorption spectroscopy Zeeman spectroscopy Daylight measurements Mercury concentration detection in the environment Theoretical studies of the Ridberg atom interaction with half-cycle pulses

5 COST Action 529, Mierlo, G.Revalde, ASI Atomic absorption and self- absorption method The light from the unit volume can be absorbed by the rest of the plasma source Unit volume One can obtain the optical density by changing the length of the plasma source Plasma source

6 COST Action 529, Mierlo, G.Revalde, ASI ab l1l1 l2l2 mirror Discharge vessel 1. Method using a mirror A – the “relative absorption” I a, I b – the intensity of the plasma sources a and b r – the reflection coefficient of the mirror l 1, l 2 – the lengths of the plasma sources a and b

7 COST Action 529, Mierlo, G.Revalde, ASI 2. Method using a spectral light source The precision of the method can be improved by placing the line spectra light source instead of the mirror. A – the “relative absorption” I L – the intensity of the lamp (plasma is off) I P – the intensity of the plasma (lamp is off) I L+P – the intensity of the plasma and lamp In this experimental work the high-frequency electrodeless discharge lamp (HFEDL) have been used

8 COST Action 529, Mierlo, G.Revalde, ASI Determined concentrations for level s 5 using both methods The concentrations for the metastable level s 5 determined with two methods coincide within the experimental error. p = 0.5 mbar, P = 2.26 kW Gas flow: 200 sccm Ar/ H2 mixture (Ar % %)

9 COST Action 529, Mierlo, G.Revalde, ASI Hg/Ar low pressure inductive coupled plasmas The intensity of the resonance line 253.7nm versus the cold spot temperature. Dashed line – numerical calculation, points – experimental data.. N. Denisova, G.Revalde, A. Skudra, G.Zissis, High-frequency electrodeless lamps in an argon-mercury mixture, J.Phys.D.Appl.Phys. 38, 2005,

10 COST Action 529, Mierlo, G.Revalde, ASI Electrodeless discharge lamps Bright radiators in the broad spectral range (VUV - IR); Filled with gas or metal vapor+buffer gas like Sn, Cd, Hg, Zn, Pb, As, Sb, Bi, Fe, Tl, In, Se, Te, Rb, Cs, I 2, H 2, He, Ne, Ar, Kr, Xe, Dy,Tu(first samples) as well as combined Hg-Cd, Hg-Zn, Hg- Cd-Zn, Se-Te etc (also isotope fillings, as example Hg 202 ) etc. No electrodes – long working life Inductive coupled/ capacitatively coupled; Hf, Rf Electromagnetic field excitation; Different designs and types in dependence on application

11 COST Action 529, Mierlo, G.Revalde, ASI Line shape studies Capillary Lamp Capillary Monochromator Power supply Fabry – Perrot interferometer PhotomultiplierComputer Lens Vacuum chamber Amplifier Spectral line shape measurements and modelling, to control self- absorption and to get important plasma parameters (such as gas temperature, lower state density, etc) Zeeman spectrometer

12 COST Action 529, Mierlo, G.Revalde, ASI Theoretical approach Observed spectral line profile: (1) where f ’(x) - real profile, f’’(x) - instrumental function,  (x) - function characterizing random errors. 2 methods to find the real spectral line shape: Line shape modeling – non-linear multi-parameter fitting of the model profile to an experimental spectral line profile by varying unknown parameters Solving the inverse task using Tikhonov’s regularization method

13 COST Action 529, Mierlo, G.Revalde, ASI Modelling Model includes the basic factors causing the spectral line broadening in HF discharge: Doppler, natural, collision.. These effects are accounted by means of the Voigt profile. Multiple overlapping lines are generated including hyperfine splitting and isotope shifts. Self-absorption (one beam approximation) The resulting profile is a convolution of the manifold of self-absorbed profiles and the instrument function. The resulting profile is fitted to the experimental lines by means of a non-linear multi-parameter fitting procedure. Typically the following parameters are fitted: atom temperature, collisional broadening, optical density, light source inhomogenity, width of the instrument function.

14 COST Action 529, Mierlo, G.Revalde, ASI Solving the inverse problem by Tikhonov´s method

15 COST Action 529, Mierlo, G.Revalde, ASI

16 COST Action 529, Mierlo, G.Revalde, ASI Mercury 185 and 254 nm line examples Mercury 185 and 254 nm line examples in dependence on the T cold spot (0 o C-100 o C) Ar/Hg 202 (99.8 %) 253,7 nm line Modelling

17 COST Action 529, Mierlo, G.Revalde, ASI 185 nm resonance line i=200 mA Reconstructed shapes

18 COST Action 529, Mierlo, G.Revalde, ASI Hg nm line intensity time dependance Plasma/wall interaction Working life studies

19 COST Action 529, Mierlo, G.Revalde, ASI Blackening of the walls of the vessel in the capillary lamp

20 COST Action 529, Mierlo, G.Revalde, ASI 12 nm z-range X, Y range 3  m Images of the vessel surfaces obtained by AFM: a) without plasma treatment b) after plasma treatment

21 COST Action 529, Mierlo, G.Revalde, ASI Regular daylight study – 3 years experience Relative daylight at 12:00 during 2004

22 COST Action 529, Mierlo, G.Revalde, ASI Spectral changes Wavelength, nm Daylight in the winter and summer

23 COST Action 529, Mierlo, G.Revalde, ASI Mercury concentration detection in air in real time with 2 ng precision GPS Riga’s city example

24 COST Action 529, Mierlo, G.Revalde, ASI Mercury concentration measurements in the criminalistics

25 COST Action 529, Mierlo, G.Revalde, ASI Mercury rest in cartridge cases after the shot Time after the shot Hg concentration

26 COST Action 529, Mierlo, G.Revalde, ASI


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