Details of interaction between the blackbody radiation and neutral lithium atoms were studied in the temperature ranges
T = 100-2000 K. The rates of thermally induced decays, excitations and ionization were calculated for S-, P- and D-series
of Rydberg states in the Fues' model potential approach. The quantitative regularities for the states of the maximal
rates of blackbody-radiation-induced processes were determined. Approximation formulas were proposed for analytical
representation of the depopulation rates.
Theoretical treatment of the magnetoelectric Jones birefringence and dichroism is developed through the bilinear in static
electric and magnetic field dipole-forbidden corrections to the amplitude of Rayleigh scattering. In particular cases of
orientation of the static fields relative the polarization and wave vectors of monochromatic radiation, the amplitude determines
corrections to the refractive index of atomic gas responsible for (i) the Jones birefringence and dichroism, (ii) linear
birefringence and dichroism and (iii) directional anisotropy for the monochromatic wave. The analytical equations and
numerical data for the indicated corrections, calculated for alkali atoms, determine optimal conditions for observing the
effects in vapours. For resonance on D state essential enhancement is discovered in the frequency dependence for the ratio
of refractive index anisotropy of the Jones effect to the square-root product of corresponding anisotropy determining the
Kerr and Cotton-Mouton effects.
Polarization dependence of amplitude for resonant magnetic-field-induced coherent mixing of two collinear laser waves may be used for separating M1 and E2 contributions to n12P1/2(3/2) - n22P3/2(1/2) dipole-forbidden
transition in atoms. The interference between E2 and Ml terms of the amplitude may cause linear polarization and circular dichroism effects. The dependencies of the two effects on the width and splitting of resonance levels, on resonance detuning, on relative directions of steady and alternating field vectors are determined. Numerical data are presented for frequency summation of two laser waves on Cs, Rb and K atoms.
A static electric field may induce essential changes to the cross section for the magnetic-field-induced coherent frecuency mixing of two laser waves, modifying the cross-section dependence on the magnetic field and polarization vectors of incident waves, which depends on the ratio of M1/E2 contributions to n12P1/2(3/2) - n22P3/2(1/2) radiation transition amplitude. Relations between the M1/E2 ratio and quantitative characteristics of polarization asymmetry in cross section are determined. Calculated numerical data are presented for coherent mixing of two laser waves on Cs, Rb and K atoms.
The effect is determined of a steady electric or/and magnetic field on coherent frequency mixing of a two-colour radiation in atoms. Analytical formulas for the cross section dependence on polarization have been derived which provide information on a possible way to determining E2/M1 amplitude ratio from the efficiency of the de-field-induced coherent process for collinear laser waves. The polarization-dependent properties of the process’ cross section are determined analytically in the case of Indium and Thallium atoms.
The polarization dependence of a two-colour frequency mixing in free atoms may be used for determining the ratio of E2/M1 contributions to an amplitude of a dipole-forbidden radiation transition. The details are presented for Indium and Thallium atoms where this ratio represents an important quantity determining parity nonconservation effects on atomic optical spectrum.
Frequency shifts of the spin-forbidden 3Pj-1S0 transitions for Mg, Sr and Yb atoms due to external laser field are calculated, based on a combination of measured atomic parameters (transition energies) and perturbation theory. Calculations of the higher-order dynamic Stark effect have been performed in connection with precise measurements on cooled and trapped atoms and the design of the ultra stable optical clock in an engineered light shift trap. Dispersion properties of the polarizability and hyperpolarizability components and their behavior in the vicinity of both resonances and so-called “crossing points” for the upper and lower atomic states, are analyzed. The calculation of the radial matrix elements is carried out with the use of the Green’s function method on the model potential approximation. The Green’s function in this approach has a simply analytical representation and enables one obtain the matrix elements in the form of rapidly convergent hypergeometric-type series.
The possibility of laser overheating of tumors in comparison with normal tissues at the same laser actions was explained by means of computer calculations. This effect of overheating of tumors was called selectivity of laser actions on the tumors. The experiments on the experimental animals gave the results which were in a good agreement (qualitatively) with our calculations. These computer calculations of tissues heating can be used for photodynamic therapy and laser therapy also.
The circular dichroism (CD) effect is predicted in a specific case of a two-color ionization of atoms, due to interfering a dc field-induced resonance two-photon ionization by electromagnetic radiation with frequency (omega) and the one- photon ionization by the wave with frequency 2(omega) . The maximum degree of CD may be observed in the range of fields where the probability for the dc field-induced two-photon ionization becomes comparable with that of the single-photon process and exceeds essentially the field-free two-photon ionization probability. The effect is sensitive to the relative phase between the two ac field components. The atomic parameters for this effect in alkali atoms are calculated. The range of fields is determined, for which the dichroism becomes observable. The use of the effect to control the branching ratio and the relative phase of the two radiations is discussed.
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