Laboratory description

    The main research area is a non-thermal plasma investigation, application and diagnostics by means of different, mainly,  high-resolution spectroscopy methods. The scientific work of the high-resolution spectroscopy laboratory was started in 1973. First, the excitation energy transfer processes in collisions of the second kind between atoms were investigated. The most important study object was the mixture of mercury and thallium. The method of spectral line shape measurements by means of pressure scanned high-resolution Fabry-Perrot interferometer was put into practice and gradually developed. Beginning from 80's till now, the group deals with the development of high-frequency electrodeless discharge lamps. The investigation and optimisation of these lamps for use in scientific apparatus was carried out. On the basis of high-frequency discharge plasma investigations, a new technology of production of high-frequency electrodeless lamps, containing pure rare and other gases (He, Ne, Ar, Kr, Xe, H₂) as well as metals Hg, Te, Se, Cd, Bi, Zn, Tl, Sn, Sb, Pb, As, Rb, In and multi-element fillings, like Hg + Cd, Hg + Zn, Hg + Zn + Cd, Se+Te, In+Sb was developed (13 patents). Special attention has been paid to preparation and investigation of electrodeless light sources filled with separate mercury isotope and combined elements for their use in high-precision Hg-vapour analyser and quantum magnetometers. The mercury-argon discharge plasma is under the investigation in order to evaluate the discharge efficiency. The excitation and ionisation of plasma, the spectral line profiles and intensities versus the high-frequency discharge conditions have been studied using time and spatially resolved spectroscopy methods. By the means of mathematical modelling and curve-fitting method of the interferometric data, the discharge parameters and interaction constants have been estimated.

Other direction of activities is concerned with the spectroscopy of ions of different isotopes, stored in the Paul, or Penning traps. In order to determine fundamental constants of hyperfine interaction, differential hyperfine anomaly, g-factors the hyperfine-structure measurements with both, the optical-microwave double resonance method and electron-cyclotron techniques, are applied. This part of work is done in collaboration with Prof. G. Werth group in Mainz and began in 1993.

Recently new efforts were initiated to investigate low pressure non-equilibrium plasmas. Such plasmas have become of growing interest in the field of plasma processing. In particular, emission and absorption spectroscopy (TDLAS) are dominantly applied for the investigation of these chemically active plasmas (Collaboration with Prof. J. Röpcke group, Institute of Non-Thermal Plasma Physics, Greifswald).

Scientific results of investigations are published in international and national journals, represented in conferences as posters and oral presentations and registered as patents (about 150 publications). Good results are achieved in understanding of physical and chemical processes taking place in low-temperature and low-density high- frequency (HF) plasmas. The obtained physical parameters are necessary to create theoretical models of HF-discharge. Significant physical constants, basically important for atomic physics, are measured.

Our results are applied to develop new techniques and scientific devices, such as, atomic absorption devices, spectrometers for precise measurement of the breaking index of glass, Zeeman spectrometers, quantum standards. In some past years, there are efforts to apply high-frequency electrodeless discharge for lightening purposes. In contrast to conventional luminescent lamps the new type of electrodeless lamps are promising high economic effect: high lumen output, high system efficacy and long life time. Such lamps are free from usual limitations imposed by electrodes. To solve the problem of effective lighting, the group takes part in the COST action Nr. 529 "Efficient lighting for 21st century" (2001-2006) where about 15 countries are involved. Our group is responsible for the work of the task-group " Innovative light sources- electrodeless lamps". 

Mercury Pollution Determination in Air Using Zeeman Atomic Absorption Spectrometer RA 915+ (High Tech in Latvia 2008)

Some selected publications:

• Kraulina E.K., Liepa S.J, Skudra A.J, Spectral Lines of Thallium in Sentisized Fluorescence in the Mixture of Mercury and Thallium, Opt. Spectr, 40, p. 767-769 (1976).

• Skudra A., Bulishev A., Suvorov A., Kraulina E., Liepa S. Some problems of Kinetics in Sensitized Fluorescence. Abstr. of the  VI  Int. Conf. of Atomic Physics, Riga,  p. 270-271 (1978).

•  Kraulina E.K., Liepa S.J, Lezdinsh A., Skudra A.J, Excitation energy transfer in the collisions of mercury and thallium atoms, Opt. Spectr. 47, p.51-55 (1979).  

• Lezdinsh A.E., Skudra A.J., Preparation method of the mercury isotope high-frequency electrodeless lamp, Patent UdSSR, № 1326089 (1985).

• Lezdinsh A.E., Putnina S., Skudra A., Gagov V. Spectral characteristics of high-frequency electrodeless mercury lamps. XI National Conf. on Atomic Spectroscopy with Int. Particip, Varne-Djurba, Bulgaria, p.361-364 (1986).

• A. Bulishev, N. V. Denisova, A. Skudra, Optical characteristics of electrodeless HF discharge in Argon and Krypton, Opt. Spectrosc. 67, N4, p.788-791 (1989).

• D.Berzina, S. Putnina, G. Revalde, A. Skudra. High-frequency electrodeless lamps with combined Hg-Cd filling. In: CANAS, Moscow, USSR,  p. 89 (1990).

• A.Skudra, N. Stankov, Lamp for photochemical separation of mercury isotopes, Patent  UdSSR , No: 1672803 (1991).

• A.Skudra, V. Arājs, Set-up for lightening, Patent  UdSSR ,No: 1749951 (1992).

• G. Revalde, D. Berzina, V. Lhevkovski, L. Luizova, S. Putnina, P. Reppo, A. Semakov. The automatic spectrometric complex for spectral line profile measurements. J.Appl.Spectr., V56, N4,  p. 681-686 (1992).

• A.Skudra, G.Revalde, N. Stankov, Selective mercury ion spectral line source, Patent  UdSSR , No:1722137 (1992). 

• A.Skudra, High frequency helium electrodeless light sources, in the book High-frequency electrodeless light sources,   Acta Universitatis Latviensis, V573, Riga,  p.67-75 (1992).

• K. Enders, O. Becker, L. Brand, J. Dembczynski,  G. Marx, G. Revalde, P. M. Rao, E. Stachowska, G. Werth. Hyperfine-structure measurements in the ground state of radioactive ¹⁵⁰ Eu⁺ ions,  Phys.Rev. A 52, N6,  p. 4434 - 4438 (1995) .           

• N. Denisova, A.Skudra. A collisional-radiative model for high-frequency discharges, In proceedings of the 8^th International Symposium on the Science & Technology of Light Sources LS-8, Greifswald, Germany, p. 388-389 (1998).

• G. Revalde, K. Enders, E. Stachowska, G. Marx, Ch. Zölch, J. Dembczynski, G. Werth. Measurements of Hyperfine Structure of Stable and Instable Eu+ in a Paul Trap, Las. Physics 8, No. 3, p.657-663 (1998).

• G. Revalde, A. Skudra. Optimisation of mercury vapour pressure for the high-frequency electrodeless light sources, J. of Physics D: Applied Physics, 31, p. 3343-3348 (1998).

• A. Skudra, G. Revalde. Mathematical modelling of the spectral line profiles in the high-frequency discharge, J. Quant. Spectrosc. Radiat. Transfer. 61, No. 6, p. 717-728 (1999).

• S. Trapp, G. Marx, G. Tommaseo, A. Klaas, A. Drakoudis, G. Revalde, G. Szawiola, G. Werth, Hyperfine structure and g-factor measurements on Ba+ and Eu+ isotopes, Hyperfine interactions 127, 57-64 (2000).

• A. Skudra, G. Revalde, N. Denisova,  Optimum of filling of rare gas and hydrogen HF-electrodeless light sources, In Proceedings HTMC-X, FSZ Jülich GmbH, p.305-308 (2000).

• I.Bersons and A.Kulsh, Classical form factor for nlm n'l'm transitions in the hydrogen atom, Physics Letters A 277, p. 223-226. (2000).

• N. Lang, M. Kalatchev, B.P. Lavrov, L. Asare und J. Röpcke, Analysis of nonthermal effects in normal and abnormal hollow cathode discharge containing hydrogen, DPG E-Verhandlungen, Bonn, P 16.41 (2000)

• G. Revalde, A. Skudra, The HF-electrodeless light source cleaning method, In Proceedings HTMC-X, FSZ Jülich GmbH, p. 301-304  (2000).

• G. Revalde, M. Osiac, K. Li, J. Rôpcke, J. Meichsner, Tunable diode laser absorption studies of hydrocarbons in RF HMDSO plasmas, 32 ^nd EGAS, Vilnius, p. 309 (2000).

• J Meichsner, K Li, J Röpcke, G Revalde and M Osiac, Investigation of Low - Molecular Products Hexamethyldisiloxane (HMDSO) Conversion in RF-Discharge, In Abstracts of XV^th ESCAMPIG, Lillafüred, Hungary, 434-435(2000).

• I. Bersons, G. Revalde, A. Skudra,  Spectral Line  Shape Modeling in HF-Discharge,  Proceedings of the  9th  International Symposium on the Science technology of Light  Sources, Cornell  University, Ithaca, NY, USA, p. 269-270 (2001).

•  J. Skudra, G. Revalde, Z. Gavare, Mercury capillary electrodeless high-frequency discharge for HG analysers”, In proceedings of ESCAMPIG 16/ICRP 5, Grenoble, Editors: N. Sadeghi, H. Sugai, p.367-368 (2002).

• J. Röpcke, G. Revalde, M. Osiac, K. Li, J. Meichsner, Tunable Diode Laser Absorption Studies of Hydrocarbons in RF Plasmas Containing Hexamethyldisiloxane, Plasma Chemistry & Plasma Processing 22, N1, p. 139 -159 (2002).

• G. Tommaseo,  T. Pfeil,  G. Revalde,  G. Werth,  P. Indelicato  and J.P. Descluaux, “The g_j-factor in the ground state of  Ca⁺”,  European Physical Journal D 25, 113-121 (2003).

• S. Trapp,  G. Tommaseo,  G. Revalde,  E. Stachovska,  G. Szawiola and G. Werth,  Ion  trap  nuclear resonance on  ¹⁵¹Eu⁺,  European Physical Journal D 26, 237-244 (2003)

•   N. Denisova, A.Skudra, Radiative Characteristics of High-Frequency Electrodeless  Helium Lamps, Opt. Spectr. 95, N6, p. 945-949 (2003).

• A.Ganeev, Z. Gavare, V.I.Khutorshikov , S.V.Khutorshikov, G. Revalde, A.Skudra  G.M.Smirnova, N.R.Stankov, High-frequency electrodeless discharge lamps for atomic absorption, Spectrochemica Acta B 58, N5, 879-889 (2003).

•  N. Denisova and A. Skudra, High-frequency electrodeless discharges in helium, Plasma Sources Sci. Technol. 13, p. 594-599 (2004).

•  G.Revalde, B. Polyakov, Z. Gavare, A.Skudra, S. Sholupov, Investigation of HF mercury low-pressure discharge plasma – wall interaction, Proceedings of the 7th international conference on modification of materials with particle beams and plasma flows, Tomsk, Russia, p.206-208 (2004).

•  A.Skudra, G.Revalde, N. Denisova, Investigation of light source wall cleaning methods by means of HF plasma”, Proceedings of the 7th international conference on modification of materials with particle beams and plasma flows, Tomsk, Russia, p.462-464 (2004).

•  Z. Gavare, G. Revalde, A. Skudra, A. Ganeev, S. Sholupov, High-frequency electrodeless lamps for application in atomic absorption analysis,  Proceedings of the 10th International Symposium on the Science and Technology of Light Sources, Toulouse,  IoP Conference series Nr. 182, Editor G. Zissis, IoP Publishing Bristol and Philadelphia, p. 289-290 (2004).

•  I. Bersons, Z. Gavare, G. Revalde, A. Skudra, N. Denisova, Diagnostics of the spectral properties of HF electrodeless mercury and rare gas lamps for different applications,Proceedings of the 10th International Symposium on the Science and Technology of Light Sources, Toulouse, IoP Conference series Nr. 182, Editor G.Zissis, IoP Publishing Bristol and Philadelphia, p. 315-316 (2004).

•  N. Denisova, A. Skudra, G. Revalde, G. Zissis, Numerical and experimental investigation of high-frequency electrodeless lamp in argon-mercury mixture, Proceedings of the the 10th International Symposium on the Science and Technology of Light Sources, Toulouse,  IoP Conference series Nr. 182, Editor G. Zissis, IoP Publishing Bristol and Philadelphia, p. 221-222 (2004).

• Z. Gavare, G. Revalde, A. Skudra, A. Ganeev, S. Sholupov, High frequency electrodeless lamps for application in atomic absorption analysis, International conference EcoBalt 2004 abstracts, Riga, p.30-31 (2004).

• G.Revalde, N.Denisova, Z.Gavare, A.Skudra, Diagnostics of capillary mercury-argon high-frequency electrodeless discharge using line shapes, Journal of Quantitative Spectroscopy and Radiative Transfer 94, p. 311-324 (2005).

• N.Denisova, G.Revalde, A.Skudra, Radial properties of the high-frequency electrodeless lamps in an argon-mercury mixtures, Journal of Physics D, Applied Physics 38, p. 3269-3274 (2005)

•  N.Denisova, G.Revalde, A.Skudra, G.Zissis, N.Zorina, High-frequency electrodeless lamps in argon-mercury mixtures, Journal of Physics D, Applied Physics 38, p. 3275-3284 (2005).

• A.A. Ivanenko, N.B. Ivanenko, M.A. Kuzmenkov, E.M. Jakovleva, A. Skudra, M.N. Slyadnev, A.A. Ganeev, Direct and rapid analysis of ambient air and exhaled air in Zeeman Spectrometer by means of aerosols electrostatic precipitation into the atomizer furnace, Analytical and Bioanalytical Chemistry 381, 713 (2005).

• A. Skudra, G. Rēvalde, Z. Gavare, J. Silinsh, N. Zorina, B. Polyakov, Study of the high-frequency inductive coupled discharge plazma interaction with walls, Plasma processes & Polymers, 2007, 4, S1026 – S1029.

• G.Revalde, A.Sholupov, A.Skudra, N.Zorina, Investigation of Hg resonance 184.9 nm line profile in a low-pressure mercury-argon discharge, JQSRT, 107 (2007) 164–172

• M. Berzins, N. Denisova, Z. Gavare, R. Veilande, N. Zorina, Determination of gas temperature of hydrogen containing high-frequency electrodeless lamps using (2-2)Q Fulcher-α bands of H2 molecule, Proceedings of the 11th International Symposium on the Science and Technology of Light Sources (LS – 11), May 20th-24th, 2007, Shanghai, China, p. 149 – 150

• N. Denisova, Z.Gavare, G.Revalde, A.Skudra, Tomographic reconstruction of the spatial profiles of emitting mercury atoms in the vertically and horizontally operating capillary discharge lamp, Proceedings of the 11th International Symposium on the Science and Technology of Light Sources (LS – 11), May 20th-24th, 2007, Shanghai, China, p. 295 – 296

•  E. Bogans, G. Revalde, A. Skudra, S. Sholupov, A. Svagere, Mercury plasma sources for Hg atomic analyser, Proceedings of the 11th International Symposium on the Science and Technology of Light Sources (LS – 11), May 20th-24th, 2007, Shanghai, China, p. 615 – 616

•  N. Zorina, G. Revalde, A. Skudra, Calculation of the real spectral line shape by solving the ill-posed inverse problem, Proceedings of XXVIII International Conference on Phenomena in Ionized Gases, Czech Republic, Prague, July 15 – 20 (2007) 543 - 545.

• M. Berzins, Z. Gavare, G. Revalde, J. Silinsh, Determination of gas temperature of hydrogen containing high-frequency electrodeless lamps, Proceedings of XXVIII International Conference on Phenomena in Ionized Gases, Czech Republic, Prague, July 15 – 20 (2007) 1576 - 1578.

• 1. E. Bogans, Z. Gavare, A. Skudra, G.Bebris, Forensic analysis using Mercury concentration measurements in shooting products by Zeeman atomic absorption spectroscopy, Abstracts of 2007 European Winter Conference on Plasma Spectrochemistry, Italy, Taormina, February 18 – 23, 2007, abstract number: MoPo71

•  Z. Gavare, E. Bogans, A. Skudra, S. Sholupov, Mercury pollution determination in Riga by Zeeman atomic absorption spectroscopy, Abstracts of 2007 European Winter Conference on Plasma Spectrochemistry, Italy, Taormina, February 18 – 23, 2007, abstract number: TuPo60

• A. Skudra, D. Erts, N. Zorina, Z. Gavare,G. Revalde, Light source wall treatment and surface changes, Abstracts of Nanotech Northern Europe 2007, Helsinki, Finland, March 27 – 29, 2007, 68 – 69.

• N. Zorina, G. Revalde, A. Skudra, Calculation of the real spectral line shape by solving the ill-posed inverse problem, Abstracts of XXVIII International Conference on Phenomena in Ionized Gases, Czech Republic, Prague, July 15 – 20 (2007) 48.

• M. Berzins, Z. Gavare, G. Revalde, J. Silinsh, Determination of gas temperature of hydrogen containing high-frequency electrodeless lamps, Abstracts of XXVIII International Conference on Phenomena in Ionized Gases, Czech Republic, Prague, July 15 – 20 (2007) 193.

• A. Skudra, N. Zorina, Z. Gavare, J. Silinsh, D. Erts, Light source inner surface changes depending on treatment , Abstracts of 9th International Workshop on Plasma Based Ion Implantation & Deposition (PBII&D 2007), Leipzig, Germany, Sept. 2 – 6 (2007) 101.

• Z. Gavare, E. Bogans, A. Skudra, A. Svagere, Mercury pollution surveys in Riga (Latvia), Abstracts of 11th Workshop on Progress in Analytical Methodologies for Trace Metal Speciation, Munster, Germany, Sept. 4 – 7 (2007) 78.

•  E. Bogans, Z. Gavare, N. Zorina, G. Bebris, Application of mercury determination by Zeeman atomic absorption spectroscopy in forensic analysis, Abstracts of 11th Workshop on Progress in Analytical Methodologies for Trace Metal Speciation, Munster, Germany, Sept. 4 – 7 (2007) 118.

• A. Skudra, N. Zorina, Z. Gavare, M. Berzins, and D. Erts ,Light source inner surface changes depending on treatment, Physica Status Solidi C 5 (2008), No 4, 915 - 917

•  N. Denisova, E.Bogans, G.Revalde, A.Skudra, Imaging of emitting mercury atom spatial distributions in a capillary discharge lamp by using tomography approach, IEEE Transactions on Plasma Science (2008), Vol. 36, No. 4, p. 1188 - 1189.

• Z. Gavare, A. Skudra, J. Silinsh, M. Granats, Determination of helium number densities in electrodeless low-temperature high-frequency plasma, In abstracts of 19th European Conference on Atomic and Molecular Physics of Ionised Gases (ESCAMPIG -2008), Granada, Spain, 15 – 19 July (2008), 1-81

•  N.Zorina, G.Revalde, A.Skudra, Ill-posed inverse problem solving using two methods of choosing of regularization parameter, In abstracts of 19th European Conference on Atomic and Molecular Physics of Ionised Gases (ESCAMPIG -2008), Granada, Spain, 15 – 19 July (2008), 3-99

•  E. Bogans, N. B. Ivanenko, A. A. Ivanenko, A. Skudra "High-frequency electrodeless light sources for determination of polluting elements in air”, In abstracts of 4th Nordic Conference on Plasma Spectrochemistry (Nordic Plasma 2008), Loen, Norway, 15-18 June (2008) p.91.

•  Z. Gavare, E. Bogans, A. Svagere, A. Skudra "Determination of mercury concentration in the peat using RA – 915+ mercury analyzer with RP-91C attachment", In abstracts of 4th Nordic Conference on Plasma Spectrochemistry (Nordic Plasma 2008), Loen, Norway, 15-18 June (2008) p. 92.

•  N. Zorina, G. Revalde, R. Disch, Deconvolution of the Mercury 253.7 nm Spectral line shape for the use in Absorption Spectroscopy, In abstracts of the 6th International Conference “Advanced Optical Materials and Devices” (AOMD-6), Riga, Latvia, 24 – 27 August (2008), p.62.

• M. Granats, G. Revalde, Z. Gavare, Measurements of absolute line intensities of helium containing high-frequency electrodeless lamp, in abstracts of the 6th International Conference “Advanced Optical Materials and Devices” (AOMD-6), Riga, Latvia, 24 – 27 August (2008), p.63.

• A. Skudra, G. Revalde, Z. Gavare, N. Zorina, D. Erts, Study inductive coupled hydrogen and argon plasma interaction with SiO2 Glass, In Abstracts of Eleventh International Conference on Plasma Surface Engineering (PSE 2008), Garmisch-Partenkirchen, Germany, 15 – 19 September (2008), p.423.