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IAPS,

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Modelling of spectral line shapes in electrodeless discharge lamps G. Revalde1, N. Denisova2, A.Skudra1 1 High-resolution spectroscopy and light source technology ... – PowerPoint PPT presentation

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Title: IAPS,


1
Modelling of spectral line shapes in
electrodeless discharge lamps
  • G. Revalde1, N. Denisova2, A.Skudra1
  • 1 High-resolution spectroscopy and light source
    technology laboratory,
  • Institute of Atomic Physics and Spectroscopy,
    University of Latvia
  • 2 Institute of Theoretical and Applied
    Mechanics,
  • Novosibirsk, Russia
  • E-mail gitar_at_latnet.lv
  • Web http//www.atomic-physics.lv

2
Electrodeless lamps   
  • ? Bright radiators in the broad spectral range
    (VUV - IR)
  • ? Filled with a gas or metal vaporbuffer gas
  • No electrodes long working life
  • Inductive coupled/ capacitatively coupled
  • Hf, Rf Electromagnetic field excitation
  • Different designs and types in dependence on
    application

 
 
 
 
 
3
Our experience and technology   manufacturing
of electrodeless lamps containing such elements
as Sn, Cd, Hg, Zn, Pb, As, Sb, Bi, Fe, Tl, In,
Se, Te, Rb, Cs, I2, H2, He, Ne, Ar, Kr, Xe as
well as combined Hg-Cd, Hg-Zn, Hg-Cd-Zn, Se-Te
etc (also isotope fillings, as example Hg202)
etc. for different applications
4
Examples
5
Spectral line profile is important
  • to control self-absorption or radiation trapping
  • for design consideration of low pressure lamps
    for lighting application - resonance radiation
    of Hg at 185 nm and 254 nm
  • in all cases when narrow spectral line is
    necessary for atomic absorption, optical
    pumping, quantum standards, for spectral
    reference
  • to get important plasma parameters (such as gas
    temperature, lower state density, collisional
    broadening)

6
Example of atomic absorption spectrometry
  • Narrow, not self-absorbed spectral line is
    neccessary -- gt
  • to get high differential cross section
    of
  • atomic absorption --gt
  • low limits of
    detection

7
  • But with self-absorption dependent on
  • working regime
  • filling pressure,
  • filling content
  • lamp geometry
  • excitation geometry
  • Possibilty to avoid the self-absorption
    optimisation of all parameters

8
Line profile measurements
High-resolution scanning Fabry-Perrot
interferometer
9
High-resolution scanning Zeeman spectrometer for
resonance lines
10
Hg 253,7 nm
  • Natural filling Hg 202
    isotope

In dependence on the Tcold spot
On the working regime
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15
Examples of experimental and modeled profiles
Zeeman spectrometer
Fabry-Perrot spectrometer
Necessity to take into account the instrument
function, also by a small FWHM value of
instrument profile due to the influence on the
self-reversal
16
Hg202/Ar(2 Torr) experimental and modeled
profiles of 253.7 nm line, spherical discharge
17
Example, Hg 202 (99.8 ) 253,7 nm line
160 mA, Tc.spot.72oC
50 mA, Tc.spot.72oC
Distribution of the intensitites other isotopic
components (0.2 ) also fitted
18
Hg202/Ar capillary
Experiment
Reff 0,8 (dninstr 0,071 cm-1).
19
Hg202/Ar (10 Torr) capillary, 253.7 nm line,
Tcold spot 25oC
The total experimental spectral line FWHM as a
function of the HF generator current
The estimated temperature of the emitting atoms
The estimated optical density in the line center
20
Hg202/Ar (2 Torr) capillary, 253.7 nm line,
Tcold spot 65oC
21
Comparison- spherical and capillary
160 mA and T cold spot 25oC, pAr10 Torr
22
Hg visible triplett
Experimental 404.7 nm line shapes in dependence
on the HF generator current for a HF isotope
electrodeless lamp
Example of the line shape fitting of Hg 404.7 nm
line, HF generator current i100 mA. Fitted
parameters wG0,032 cm-1 wL0,002 cm-1 R0,72,
kol1,8, n13, using the model of Cowan and Dieke
23
Example of the line shape fitting of 546.1 nm Hg
line, i140 mA. Fitted parameters wG0,033 cm-1
wL0,002 cm-1 R0,8 kol35 with taking into
account the measured distributions.
  • Experimental radial distributions of Hg
    404.7 nm line intensity, emitted from HF
    electrodeless lamp by two different discharge
    power values.

24
Helium example
  • Optical density in the line center in
    dependence on the HF generator current estimated
    for 501,6 nm and 567,8 nm lines in the helium
    electrodeless discharge using the model of
    uniformly excited source.

Experimental radial distributions of He 587,6 nm
line intensity, emitted from helium HF
electrodeless lamp by two different discharge
power values.
25
  • Thank you for your attention!

26
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