Romualdas Karazija

Research

Areas of research

• Theory and interpretation of X-ray and Auger spectra of free atoms;
• Theory of complex atoms and ions;
• Applications of atomic theory in chemistry and plasma physics;
• History of physics.

Main scientific results

• The theory of X-ray and Auger spectra for atoms with open shells was generalized and developed.
  

  R. Karazija. Introduction to the Theory of X-Ray and Electronic Spectra of Free Atoms. New York–London: Plenum Press, 1996.
  Progress Report at VII All-Union Conference on the Theory of Atoms and Atomic Spectra, Tbilisi, 1981.

• The general group-diagrammatic method for the summation of atomic quantities over many-electron quantum numbers was elaborated. It gives one a possibility to derive the explicit expressions for various global characteristics of atomic spectra. Such general expressions were obtained for the asymmetry and excess of energy level spectrum, for the variance of emission spectrum as well as for the average energy and variance of Auger spectrum. These expressions were used for the investigation of spectral regularities in the isoelectronic, isonuclear and atomic sequences. Also the mean characteristics of configuration interaction in atoms were proposed: the average energy distance between interacting levels of two configurations and configuration interaction strength; their explicit expressions were derived.
  

  R. Karazija. Sums of Atomic Quantities and Mean Characteristics of Spectra. Vilnius: Mokslas, 1992, 272 p. [in Russian].
  The series of papers in Phys. Scripta 47(6), 754–764 (1993); 51(5), 566–577 (1995); 52(6), 639–648 (1995); 55(6), 667–675 (1997); 67(3), 208–218 (2003) [jointly with S. Kučas, V. Jonauskas as well as experimenters I. Martinson and S. Aksela].
  R. Karazija, S. Kučas. Summation of atomic quantities over all many-electron quantum numbers. Lith. J. Phys. 35(2), 155–170 (1995) [review paper].
  R. Karazija, S. Kučas. Average characteristics of the configuration interaction in atoms and their applications. J. Quantit. Spectr. Rad. Transf. 129, 131–144. 2013 [review paper].
  Progress Report at The Fifth European Conference on Atomic and Molecular Physics, Edinburgh, 1995.

• Some new features of the collapse of electron wavefunction were determined: collapse can take place for different terms of the same configuration and not for all equivalent electrons in atom of the same element. The properties of 3d and 4d photoabsorption and emission spectra were interpreted as caused by collapse and potential barrier effects.
  

  S.А. Kučas, А.V. Karosienė, R.I. Karazija. Localization of 4f-electron in dependence on term in 4d⁹4f configuration and its influence on the N_4,5 absorption spectra. Opt. Spectroscopy 40(4), 764–765 (1976) [in Russian].
  А.А. Maiste, R.E. Ruus, S.A. Kuchas, R.I. Karaziya, М.А. Elango. Collapse of the 4f electron in the 3d94f configuration in xenon-like ions. JETP 78(3), 941–951 (1980) [in Russian]. English translation: Sov. Phys. JETP 51(3), 474-479 (1980).
  R.I. Karaziya. Excited electron orbit collapse and atomic spectra. Usp. Phys. Nauk 135(1), 79–115 (1981) [in Russian]. English translation: Sov. Phys. Usp. 24(9), 775–794 (1981) [review paper].
  Progress Reports at VI All-Union Conference on the Theory of Atoms and Atomic Spectra, Voronezh, 1980 and at USSR/Polish seminar on the investigation of f-electron systems, Vilnius, 1988.

• The invariance of radiative and Auger widths of levels as well as of fluorescence yield was established for some class of configurations.
  

  R. Karazija. Approximate invariance of Auger and radiative widths of levels and fluorescence yield. Lit. fiz. sb./ Liet. fiz. rink. 23(1), 6–16 (1983) [in Russian].
  R. Karazija. Introduction to the Theory of X-Ray and Electronic Spectra of Free Atoms. New York–London: Plenum Press, 1996.

• Classification of states for configurations according to their parentage in the isoelectronic sequence and the new wavefunction basis for these configurations were introduced. Such a classification enables one to obtain the functional, which guarantees the orthogonality of wavefunctions to the functions of energetically lower states of the same symmetry. These results were extended by J. Kaniauskas and Z. Rudzikas while introducing the isospin formalism in atomic physics.
  

  P. Bogdanovich, R. Karazija, and J. Boruta. The orthogonality of wavefunctions to the functions of the configurations lower-lying energetically and the validity of Brillouin‘s theorem in the case of electronic configuration . Lit. fiz. sb./ Liet. fiz. rink. 20(2), 16–24 (1980) [in Russian].
  R. Karazija. Additional symmetry properties of atomic states with one and two open shells. Lith. J. Phys. 54(4), 205-216 (2014) [review paper].

• Algebraic expressions for energy of the highest multiplicity and related with them terms as well as for the ground and highest energy levels were obtained. They were applied for interpretation of the symmetry with respect to a quarter of shell for binding energies, system differences and other quantities related with the ground state of an atom.
  J. Kaniauskas, and R. Karazija. Algebraic expressions of energy for terms of the highest multiplicity and related ones, as well as for ground and highest energy levels. Lit. Fiz. Sb./ Liet. fiz. rink. 25(2), 31–41 (1985) [in Russian].
  R. Karazija, A. Udris, A. Kynienė, S. Kučas. On the symmetry with respect to a quarter of electronic shell for the intensities of the strongest lines in lanthanide spectra. J. Phys. B: Atom. Mol. Opt. Phys. 29(11), L405–L409 (1996).
  R. Karazija, A. Kynienė. On the symmetry of some properties of lanthanides with respect to a quarter of fN shell. J. Phys. Chem. A. 102(6), 897–903 (1998).

• The first detailed calculation of the cascade of elementary processes after the production of inner vacancy was performed taking into account the populations of excited states, radiative and non-radiative transitions as well as the configuration interaction. Modelling of cascades using the global characteristics of spectra was elaborated. The essential role of many-electron Auger transitions in cascades after the production of vacancies in the subvalent shells of krypton was demonstrated and the high-resolution Auger spectra, registered by the coincidence method in the 3p and 3d cascades, were interpreted.
  R. Karazija, S. Kučas. Population of Ar II и Ar III configurations during and after electron impact ionization and the structure of L_2,3. X-ray spectrum. Lit. fiz. sb./ Liet. fiz rink. 19(4), 495–504 (1979) [in Russian].
  J. Paladoux, P. Lablanquie, L. Andric, K. Ito, E. Sigemasa, J.H.D. Eland, V. Jonauskas, S. Kučas, R. Karazija and F. Penent. Multielectron spectroscopy: Auger decays of the krypton 3d hole. Phys. Rev. A 82(4), 043419, p. 1–13 (2010).
  V. Jonauskas, S. Kučas, R. Karazija. Auger decay of 3p-ionized krypton. Phys. Rev. A 84(5), 053415, p. 1–7 (2011).
  R. Karazija, S. Kučas, V. Jonauskas. Investigation of the cascades in atoms using the global characteristics of spectra. Lith. J. Phys. 44(3), 183–198 (2004) [review paper].

• Conditions for the formation of a narrow group of intense lines in the emission and photoexcitation spectra were formulated. Regularities of intense tungsten emission in the region of 5 nm, important for radiative losses in tokamaks, were established. New selection rule for the dipole transitions between configurations belonging to the same complex was introduced. It was shown that the most suitable emitter at 13.5 nm for EUV lithography from the atomic point of view are Sn⁹⁺–Sn¹¹⁺ and Sb¹⁰⁺–Sb¹¹⁺ ions.
  S. Kučas, R. Karazija. Coulomb exchange interaction between electrons in the atom and structure of complex configurations. J. Phys. B.: Atom. Mol. Opt. Phys. 24(13), 2925–2936 (1991).
  A. Bernotas, R. Karazija. Additional selection rule for some emission, photoexcitation and Auger spectra. J. Phys. B: Atom. Mol. Opt. Phys. 34(23), L741–L747 (2001).
  R. Karazija, S. Kučas, A. Momkauskaitė. Integral characteristics of spectra of ions important for EUV lithography. J. Phys. D: Appl. Phys. 39(14), 2973–2978 (2006).
  S. Kučas, R. Karazija, V. Jonauskas, A. Momkauskaitė. Interaction[r1] of 4p⁵4d^N+1 and 4p⁶4d^N–1 4f configurations in the isoelectronic and isonuclear sequences and its influence on the photoexcitation and emission spectra. J. Phys. B: Atom. Mol. Opt. Phys. 42, 205001, p. 1–10 (2009).
  R. Karazija, S. Kučas, V. Jonauskas, A. Momkauskaitė. Formation of a narrow group of intense lines in the emission and photoexcitation spectra. In: New Trends in Atomic and Molecular Physics. Springer Series on Atomic, Optical, and Plasma Physics, v. 76, 2013, Chapter 10, p. 167–188 [review paper].
  Invited Talk at 3rd International Conference on Current Developments in Atomic, Molecular, Optical and Nano Physics with Applications, Delhi, 2011.

Citation of publications (Web of Science)
Total of papers and books 790;
Total of papers [Karazija and Karaziya] 595, h = 14.