Spectroscopy of Rydberg atoms in a Black-body radiation field: Relativistic theory of excitation and ionization

Abstract

IntroductionA great progress in experimental laser physics and appearance of the so called tunable lasers allows one to access the highly excited Rydberg states of atoms. In fact this is a beginning of a new epoch in the atomic physics with external electromagnetic field. It has stimulated a great number of papers on the ac and dc Stark effect [1][2][3][4][5][6][7][8][9][10][11][12]. Conversely, the experiments with Rydberg atoms had very soon resulted in the discovery of an important ionization mechanism, provided by unique features of the Rydberg atoms. Relatively new topic of the modern theory is connected with consistent treating the Rydberg atoms in a field of the Blackbody radiation (BBR). It should be noted that the BBR is one of the essential factors affecting the Rydberg states in atoms [1]. The account for the ac Stark shift, fast redistribution of the levels' population and photoionization provided by the environmental BBR became of a great importance for successfully handling atoms in their Rydberg states.The most popular theoretical approaches to computing ionization parameters of the Rydberg atom in the BBR are based on the different versions of the model potential (MP) method, quasiclassical models. We mention a simple approximation for the rate of thermal ionization of Rydberg atoms, based on the results of our systematic calculations in the Simons-Fues MP [1]. In fact, using the MP approach is very close to the quantum defect method and other semi-empirical methods, which were also widely used in the past few years for calculating atom-field interaction amplitudes in the lowest orders of the perturbation theory. The significant advantage of the Simons-Fues MP method in comparison with other models is the possibility of presenting analytically (in terms of the hypergeometric functions) the characteristics for arbitrarily high orders, related to both bound-bound and bound-free transitions. Naturally, the standard methods of the theoretical atomic physics, including the Hartree-Fock and Dirac-Fock approximations, should be used in order to determine the thermal ionization characteristics of neutral and Rydberg atoms [2]. Note that the correct treatment of the heavy Rydberg atoms parameters in an external electromagnetic field requires using strictly relativistic models. Here we apply an energy approach [11][12][13][14][15] and relativistic perturbation theory (PT)

Relativistic theory of excitation and ionization of Rydberg atomic systems in a Black-body radiation field

“…In Table 1 we list the data of the ionization rate computing for the Rydberg sodium atom in the states (17,18D,18P) at temperatures of 300 K and 500 K: Th5 -our (relativistic MP theory) data [3], Th1-theory (nonrelativistic Simons-Fues MP) by Glukhov-Ovsyannikova [9], Th2-theory of Lehman [8], Th3-quasiclassical model by Dyachkov-Pankratov [10], Th4-theory by Beterov et al [1] and E1 -experimental data [4,5]. In whole there is physically reasonable agreement between the theoretical and experimental data.…”

“…In fact this is a beginning of a new epoch in the atomic physics with external electromagnetic field. It has stimulated a great number of papers on the ad and dc Stark effect [1][2][3][4][5][6][7][8][9][10][11][12]. The experiments with Rydberg atoms had very soon resulted in the discovery of an important ionization mechanism, provided by unique features of the Rydberg atoms.…”

Advanced Data for Hydrogen Atom in Crossed Electric and Magnetic Fields

“…In Ref, [7] it has been presented approach, based on solution of the 2-dimensional Schrödinger equation for an atomic system in adequate forms for the core potential (c.f. [25][26][27]). According to standard quantum defect theory (c.f.…”

Relativistic Calculation of the Radiative Transition Probabilities and Lifetimes of Excited States for the Rubidium Atom in a Black-Body Radiation Field

“…are based on the Coulomb approximation (CA), model potential (MP) approach, , different versions of the quantum defect method, classical and quasiclassical model approaches. The authors of the papers [3][4][5][6][7][8][9][10] applied the Coulomb approximation, quantum defect formalism, different versions of the model and pseudopotential method etc. It should be noted separately the cycles of theoretical and experimental works by Nashimento et al and especially Ryabtsev-Beterov et al [2,3], as well as theoretical works of Dyachkov-Pankratov and others (c.g.…”