University of Latvia, Faculty of Physics and Mathematics, Institute of Atomic Physics and Spectroscopy   LABORATORY  OF  THEORETICAL  PHYSICS   Specialization atomic physics: atoms in strong laser fields (multiphoton ionization, above threshold ionization, harmonic generation, ionization by the ultrashort laser pulses), atoms in dc electric field, electron atom collisions, Methods: quantum mechanical and semiclassical

    Page Contents:

Research Overview
Staff Members
Lecture Courses
Main Publications

    Research Overview

    Laboratory of theoretical physics was founded at the Institute of Physics of Latvian Academy of Sciences by Dr. V.Veldre (1926-1967) in 1958. From 1968 to 1992 the head of laboratory was Dr. R.Damburg.
    Starting from sixties papers of members of laboratory have been published mainly in European Journal of Atomic Physics B: Atomic, Molecular and Optical Physics. For more than 30 years Laboratory is well known by the international community of atomic physicists as " Riga group".
    At laboratory have worked R.Peterkop (1930-1991) and M.Gailitis (1935-1993). Their papers on Wanier law (threshold law) and on the close coupling methods in electron atom collisions were between the first in this field and are well known by international community.
    Laboratory with assistance of physicists from the University of Latvia has organized two international conferences:

• ICAP VI (VI international Conference on Atomic Physics, Riga 17-22 July 1978). Chair of local organizing committe R.Damburg

 
• ECAMP IV (IV European Conference on Atomic Physics, Riga 6-10 April 1992). Chair of local organizing committe: E.Karule

    Staff Members

• Prof. Erna Gailite-Karule   Head of the laboratory, tel.: +371-7229747, fax: +371-7820113, karule@latnet.lv
• Prof. Imants Bersons          Tel.: +371-7229747, fax: +371-7820113, bersons@latnet.lv,
• Prof. Robert Damburg        Tel.: +371-7229747, fax: +371-7820113, damburg@latnet.lv
• Prof. Agris Gailitis              Tel.: +371-2944700, fax: +371-7901214, gailitis@sal.lv
• Dr. Bernards Baranovskis   Tel.: +371-7229747, fax: +371-7820113, damburg@latnet.lv
• PhD student Arturs Kulsh    Tel.: +371-7229747. arturs@latnet.lv

    Lecture Courses

1. Quantum electrodynamics.
2. Nonlinear equations and solitons.
3. Atomic theory. Hydrogen atom.

    Main Publications

1. R.K.Peterkop "Theory of ionization of atoms by electron impact” Colorado associated University press, Boulder, Colorado 1977. Originally published by Zinatne Publishing House Riga, USSR 1975.
2. R. Damburg, R.Peterkop "Excitation of Hydrogen by Electron Collisions Allowing for Excange and 1s-2s-2p Strong Coupling”, Proc. Phys. Soc. v.80; 1962; 2p.
3. R. Damburg, R.Peterkop "Application of the Multichannel Effective Range Theory to Electron Hydrogen Scattering; Proc. Phys. Soc.”, v.80; 1962; 6p.
4. M.Gailitis , R.Damburg; The Influence of Close Coupling on Theshold Behaviour of Cross Sections of Electron-Hydrogen Scattering; Proc. Phys. Soc. v.82; 1962; 10p.
5. R.Damburg, M.Gailitis; Calculation in the Vicinity of 2s, 2p Threshold of the Cross Sections of Hydrogen Atoms by Electrons; Proc. Phys. Soc. v.82; 1962; 5p.
6. R.Damburg, M.Gailitis; Some Features of the Threshold Behavior of the Cross Sections for Excitation of Hydrogen by Electrons Due to the Existence of a Linear Stark Effect in Hydrogen; Soviet Physics JETP v.17; 1963; 4p.
7. E.Karule "Elastic scatering of low-energy electrons by alkali atoms" Phys. Lett. 1965, v.15, No 2, 137-138.
8. E.Karule, R.Peterkop "Collisions of slow electrons with alkali atoms". In:"Physics of Electronic and Atomic Collisions" New York, Science Bookerafters, 1965, 134-139.
9. E. Karule "Elastic scatering of low-energy electrons by alkali atoms" In: "Physics of Electronic and Atomic Collisions" New York, Science Bookerafters, 1965, 139-142.
10. R.Ya.Damburg and E.M.Karule "Positron Collisions with hydrogen Atoms" In: "Atomic Collisions" (Eds. V.Ya. Veldre, R.Ya. Damburg, R.Peterkop) Transl., The M.I.T Press, Massachusets institute of technology, Cambrige, Massachusets, 1966, p.40-43.
11. V.Ya.Veldre and E.M.Karule "Ionization of the hydrogen atom by slow electrons" In: "Atomic Collisions" (Eds. V.Ya. Veldre, R.Ya. Damburg, R.Peterkop) Transl., The M.I.T Press, Massachusets institute of technology, Cambrige, Massachusets, 1966, p.119-126.
12. R.Damburg, S. Geltman; Excitation or n=2 States in H by Electrons; Phys. Rev. Lett. v.20; 1968; 3p.
13. R.Damburg, R.Propin; Uber asymptotische Entwicklungen oblater Spharoidfunktionen und ihrer Eigenwerte; Journ. for reine und angew. Math. B233; 1968; 12p.
14. R.Damburg, R.Propin; On Asymptotic Expansions of Electronic Terms of the molecular ion H2+; Jour. Phys. B v.1; 1968; 10p.
15. R.Peterkop "Asymptotic form of wave function for the ionization problem”, in: "Physics of the one- and two- electron atoms” North Holland 1969.
16. I.Bersons "Electron in the quantized field of a monochromatic electromagnetic wave." JETP, 56, (1969) p.1627.
17. R.Damburg, E.Karule "A modification of the close-coupling approximation for e-H scattering allowing for the long-range interactions." Proc.Phys.Soc. 1967, v.90, No 3.
18. E.Karule "Polarization of lithium and sodium atom resonance lines excited by electron impact." J.Phys.B, 1970, v. 3, p. 860-864.
19. E.Karule "The spin polarization and differential cross sections in the elastic scatering of electrons by alkali metal atoms." J.Phys.B: Atom. Mol. Phys., v.4, 1971, p.67-70.
20. E. Karule. "On the evaluation of transition matrix elements for multiphoton processes in atomic hydrogen”, J.Phys. B: Atom. Mol. Phys., v.4, 1971, L67-L70.
21. R.Damburg, R.Propin; Rotational Structure of the Inversion Spectra of Amonia; J. Phys. B v.5; 1972; 10p.
22. R.Damburg, R.Propin; The Effect of 2s-2p Close Coupling on the Cross Sections for Excitation ot the 2p State of Hydrogen Atoms by Electrons at High Energies; J. Phys. B v.5; 1972; 7p.
23. R.Damburg; Theory for Pseudostate Expansion; VII ICPEAC Invited Papers; North-Holland Publ. Co., Amsterdam; 1972; 16p.
24. E. Karule. "Multiphoton ionization of atomic hydrogen in ground state (N16)”. In: "Atomic processes" (in russian), Riga, Zinatne, 1975, p.5-24.
25. I.Bersons "Multiphoton ionization and stimulated bremsstrahlung radiation in the case of short-range potentials." J.Phys.B: At. Mol. Phys., v. 8 (1975), p. , 3078.
26. M.Gailitis "New forms of asimptotic expansions for wavefunctions of charged-particle scattering ”, J.Phys.B: At. Mol. Phys. v.9, 1976, p.843-854.
27. R.Damburg, V. Kolosov; A Hydrogen Atom in an Uniform Electric Field; J. Phys. B v. 9; 1976; 9p.
28. E. Karule "Multiphoton ionization of atomic hydrogen" In: "Multiphoton Processes" . Invited papers of 1st Intern. Conference on Multiphoton processes, Rochester, N.Y. 1977, p.159-169.
29. E. Karule "Two-photon ionisation of atomic hydrogen simultaneously with one photonionisation", J. Phys. B: Atom. Mol. Phys.,1978, v.11, No 3, p. 441-447.
30. R.Damburg, V. Kolosov; An Asymptotic Approach to the Stark Effect for Hydrogen; J. Phys. B v. 11; 1978; 10p.
31. R.Damburg, V. Kolosov; A Hydrjgen Atom in a Uniform Electric Field III; J. Phys. B v. 12; 1979; 7p.
32. R.Damburg, V. Kolosov; Stark Effect as a Collosional Problem; XI ICPEAC in Tokio, Invited Papers; North-Holland; 1980; 10p.
33. R.Peterkop and A.Liepinsh "Investigation of threshold behaviour of ionisation cross sections”, J.Phys.B: At. Mol. Phys. v.14, 1981, p.4125-4135.
34. R.Petrkop "On the asymptotic form of wavefunction for the ionisation problem” J.Phys.B: At. Mol. Phys. , 1882, L751-L754.
35. R.Peterkop "Oscillator strengths and excitation cross sections of samarium atoms” Phys. Lett. 90A. No4, 1982, p.182-184.
36. M.Gailitis "On the series of double-excited states for the negative H ion below the N=3 threshold”, J.Phys.B: Atom. Molec. Phys. v.13, 1980, L479-L483.
37. I.Bersons "Quasiclassical approximation for stimulated bremsstrahlung radiation. JETP, 80 (1981) p.1727..
38. I.Bersons "Multiphoton ionization of highly excited atomic states." JETP, 83, (1982) 1276.
39. M.Gailitis "The influence of finite masses on the threshold behaviour of scattering in a three charged particle system”, J.Phys.B: Atom. Molec. Phys. v.15, 1982, 3423-3440
40. R.Damburg, V. Kolosov; Theoretical Studies of a Hydrogen Rydbergs Atoms in Electric Field; Rydberg States of Atoms and Molecules; Cambridge University Press; 1983; 40p.
41. R.Peterkop and A.Liepinsh " Plane-wave asymptotic form in the electron-atom ionisation problem”, J.Phys.B: At. Mol. Phys. v.18, 1985, p.2763-2775.
42. J.Cizek, R.Damburg, R. Propin, S. Graffi, V. Grecchi, H. Silverstone; 1/R Expansion for H2+ . Calculation of Expanentially Small Terms and Asymptotics; Phys. Rev. A v.33; 1985; 42p.
43. M.Gailitis "Energy partitioning in the ionisation threshold law”, J.Phys.B: At. Mol. Phys. v.19 , 1986, L697-L700.
44. E. Karule "Two-photon ionisation of excited atomic hydrogen at the photoelectric threshold and above", J. Phys. B: Atom. Mol. Phys.,1985, v.18, No 11, p. 2207-2218.
45. E. Karule. "Analytical continuation of transition matrix elements and multiphoton above-threshold ionisation of atomic hydrogen”, J. Phys. B, v. 21, No 11 (1988) p.1997- 2014.
46. Modris Gailitis and Harris J.Silverstone "On the use of asymptotic expansions”, Theor. Chim. Acta, v.73, 1988, p. 105-114.
47. M. Gailitis and N.Sakss "The form of the threshold phenomena for the excitation of mesic atoms by electrons”, J.Phys.B: At. Mol. Phys. v.21, 1988, p.351-354.
48. R.Damburg; "Hydrogen Atom in Strong Electric Field” in "Atoms in Strong Fields”; Plenum Press; 1990; 26p.
49. E. Karule "Multiphoton ionisation of atomic hydrogen by extra photons" In: "Atomic spectra and collisions in external fields". Plenum Press, New York, 1988, p. 409-416.
50. R.Damburg, R. Propin, V. Martyshchenko; Large-order Perturbation Theory for the O(2) Anharmonic Oscillator with Negative Anharmonicity and for the Double-well Potential; in ”Current Physics Sources and Comments” v.7; North-Holland; 1990; 10p.
51. R.Damburg, R. Propin, S. Graffi, V. Grecchi, E. Harrell II, H. Silverstone; 1/R Expansion for H2+: Analicity, Asymptotics and Calculations of Exponentially Small Terms; in ”Current Physics Sources and Comments” v.7; North-Holland; 1990; 4p.
52. R.Damburg, R. Propin, Yu. Ryabykh; Perturbation Theory for the Triple-well Anharmonic Oscillator; Phys. Rev. A 41; 1990; 7p.
53. E. Karule. "Above-threshold ionization of atomic hydrogen”. J. Opt. Soc. Am. B, v.7, No 4 , 1990, p. 631-638.
54. E. Karule "Integrals of two confluent hypergeometric functions." J.Phys.A: Math. Gen., 1990, v.23, No.11, p. 1969-1971.
55. E. Karule "Above-threshold ionization of atomic hydrogen." J.Opt.Soc.Am. B 1990, v.7, No 4, p. 631-638.
56. G. Alvarez, R.Damburg, H. Silverstone; "Photoionization in Atomic Hydrogen in Electric Field”, Phys. Rev. A 44; 1991; 13p.
57. E. Karule and R.H. Pratt. "Transformed Coulomb Green function Sturmia Expansion.” J. Phys. B, v. 24 (1991) p. 1585-1591
58. E.Karule "Stability of hydrogen atom in Rydberg states in a laser field." In:" Super-Intense Laser-Atom Physics" NATO ASI Series, Series B: Physics vol. 316, Plenum Press, New York , 1993
59. R.Damburg, B.Baranovskis, H. Silverstone; Ionization by an Electric Field: Line Disappearance in the Stark Effect; JETP 76 (6); 1993; 8p.
60. R.Damburg, B.Baranovskis; The Manifistation of Chaotic Behaviour of the Hydrogen Atom in the Presence of Uniform Electric Field; Kluwer Academic Publishers; Dordrecht / Boston / London; 1996; 36p.
61. E. Karule. "Multiphoton ionization of atomic hydrogen using perturbation theory.In: Advances in atomic, molecular and optical physics”, /Eds. D. Bates and B. Bederson/ - Academic Press, New York, 1991, v.27, p.265-299. /Review paper/
62. R.Damburg, B.Baranovskis, H. Silverstone; Direct 'Ionization' of the Hydrogen Atom by Photons in the Presence of an Electric Field; JETP 78 (6); 1994; 6p.
63. A.Gailitis and E.Karule. "Hydrogen Atom Level-Mixing in Strong Laser Fields”. In: "Resonance Ionization Spectroscopy" AIP Press, American Institute of Physics, New York, 1994, p. 411-414.
64. M.Gailitis, A.Gailitis "Photoabsorption of atomic Hydrogen in an external electric field”, J.Phys.B.: Atomic, Molecular and Optical Physics, v.29, No18, 1996, pp.4081-4091.

I.Bersons and A.Kulsh "Transition form factor of the hydrogen Rydberg atom." Phys.Rev. 55, (1997) p.1674:, PDF.