Astronomy Reports

Resonance scattering in a line in the presence of a weak external magnetic field

D. N. Rachkovskiı̆

Published Sep 1, 2005• 0 citations

Abstract

The theory required to calculate the phase matrix for resonance scattering in the presence of a magnetic field is set out. Interference effects between radiation from individual magnetic sublevels of the atom are taken into account. Errors in the algorithms used to calculate the phase matrix published earlier by other authors are identified.

DOI: 10.1134/1.2045324

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Astronomy Reports

Resonance scattering in a line in the presence of a weak external magnetic field

D. N. Rachkovskiı̆

Published Sep 1, 2005• 0 citations

Publisher

Abstract

DOI: 10.1134/1.2045324

Related papers

Scattering of Polarized Radiation by Atoms in Magnetic and Electric Fields

Yee Yee Oo, K. N. Nagendra, Sharath Ananthamurthy +1 more

arXiv:astro-ph/0509775Sep 26, 20050 citations

Resonant scattering in the presence of an electromagnetic field

Leonard Rosenberg

The theory of resonant reactions, in the projection-operator formulation of Feshbach, is generalized to account for the presence of an external electromagnetic field. The theory is used as the basis for the construction of low-frequency approximations for the transition amplitude. Results obtained here for scattering in a laser field confirm earlier versions of the low-frequency approximation when the resonances are isolated. However, if there are several closely spaced resonances additional terms must be included (their importance magnified by the appearance of near singularities) which account for the effect of radiative transitions between pairs of nearly degenerate resonant states. The weak-field limit of this result yields a low-frequency approximation for single-photon spontaneous bremsstrahlung which, through the inclusion of correction terms associated with closely spaced resonances, provides an improvement over the Feshbach-Yennie version derived some time ago. A separate treatment is required to deal with the limiting case of a static external field and this is worked out here in the context of a time-dependent formulation of the scattering problem. Linear and quadratic Stark splitting of the resonance positions, and resonance broadening due to the tunneling mechanism, are expected to play a significant role in the static limit and these effects are included in the approximation derived here for the transition amplitude.The theory of resonant reactions, in the projection-operator formulation of Feshbach, is generalized to account for the presence of an external electromagnetic field. The theory is used as the basis for the construction of low-frequency approximations for the transition amplitude. Results obtained here for scattering in a laser field confirm earlier versions of the low-frequency approximation when the resonances are isolated. However, if there are several closely spaced resonances additional terms must be included (their importance magnified by the appearance of near singularities) which account for the effect of radiative transitions between pairs of nearly degenerate resonant states. The weak-field limit of this result yields a low-frequency approximation for single-photon spontaneous bremsstrahlung which, through the inclusion of correction terms associated with closely spaced resonances, provides an improvement over the Feshbach-Yennie version derived some time ago. A separate treatment is required to deal with the limiting case of a static external field and this is worked out here in the context of a time-dependent formulation of the scattering problem. Linear and quadratic Stark splitting of the resonance positions, and resonance broadening due to the tunneling mechanism, are expected to play a significant role in the static limit and these effects are included in the approximation derived here for the transition amplitude.

Physical Review ANov 1, 198310 citations

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Population dynamics for multilevel systems in the external magnetic field

T. Ya. Karagodova, Anna V. Kuptsova, Andrey A. Eliseev

Coherent population trapping effect is widely studied for simple three-level systems of different types ((Xi) , (Lambda) , V). For real atoms situation is more complicated. Atomic levels are degenerated one and in the presence of external fields coupling of magnetic sublevels appears due to as radiation, so magnetic fields, leading to the systems of levels of the higher order. Our theory and model of calculation for interaction of multilevel atom with intense radiation field at the presence of external magnetic field have been applied for considering coherent population trapping effect for such systems.Coherent population trapping effect is widely studied for simple three-level systems of different types ((Xi) , (Lambda) , V). For real atoms situation is more complicated. Atomic levels are degenerated one and in the presence of external fields coupling of magnetic sublevels appears due to as radiation, so magnetic fields, leading to the systems of levels of the higher order. Our theory and model of calculation for interaction of multilevel atom with intense radiation field at the presence of external magnetic field have been applied for considering coherent population trapping effect for such systems.

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Nonlinear ring structures in forward scattering of resonant monochromatic laser radiation

Peter Jungner, Anne Lindberg, Birger Stahlberg

We present experimental and theoretical investigations of a Gaussian laser beam interacting with Zeeman-tuned J=1\ensuremath{\rightarrow}J=0 atomic systems. In our experiment a single-mode cw dye-laser beam traverses a neon discharge in a longitudinal magnetic field. The excited neon transitions used for these studies are 1 ${\mathit{s}}_{4}$ (J=1,g=1.464)\ensuremath{\rightarrow}2 ${\mathit{p}}_{3}$ (J=0) and 1 ${\mathit{s}}_{2}$ (J=1,g=1.034)\ensuremath{\rightarrow}2 ${\mathit{p}}_{1}$ (J=0). In the laser-induced forward-scattered light, dark and bright ring-shaped structures are observed. The ring structures are investigated as a function of the magnetic detuning of the m=\ifmmode\pm\else\textpm\fi{}1 sublevels and as a function of the laser-beam power. We find that the line shapes of the spectra, i.e., the forward-scattered light intensities as a function of the magnetic detuning, are sensitive to the transverse intensity distribution of the laser beam. Analytical expressions based on a semiclassical theory are derived and the calculated results on the ring structures and the spectra are compared with the experimental results. Good agreement between the calculated and the experimental results are obtained only when the transverse effects are taken into account.We present experimental and theoretical investigations of a Gaussian laser beam interacting with Zeeman-tuned J=1\ensuremath{\rightarrow}J=0 atomic systems. In our experiment a single-mode cw dye-laser beam traverses a neon discharge in a longitudinal magnetic field. The excited neon transitions used for these studies are 1${\mathit{s}}_{4}$(J=1,g=1.464)\ensuremath{\rightarrow}2${\mathit{p}}_{3}$(J=0) and 1${\mathit{s}}_{2}$(J=1,g=1.034)\ensuremath{\rightarrow}2${\mathit{p}}_{1}$(J=0). In the laser-induced forward-scattered light, dark and bright ring-shaped structures are observed. The ring structures are investigated as a function of the magnetic detuning of the m=\ifmmode\pm\else\textpm\fi{}1 sublevels and as a function of the laser-beam power. We find that the line shapes of the spectra, i.e., the forward-scattered light intensities as a function of the magnetic detuning, are sensitive to the transverse intensity distribution of the laser beam. Analytical expressions based on a semiclassical theory are derived and the calculated results on the ring structures and the spectra are compared with the experimental results. Good agreement between the calculated and the experimental results are obtained only when the transverse effects are taken into account.

Physical Review AAug 1, 19934 citations

{\mathit{s}}_{4}

(J=1,g=1.464)\ensuremath{\rightarrow}2

{\mathit{p}}_{3}

(J=0) and 1

{\mathit{s}}_{2}

(J=1,g=1.034)\ensuremath{\rightarrow}2

{\mathit{p}}_{1}

(J=0). In the laser-induced forward-scattered light, dark and bright ring-shaped structures are observed. The ring structures are investigated as a function of the magnetic detuning of the m=\ifmmode\pm\else\textpm\fi{}1 sublevels and as a function of the laser-beam power. We find that the line shapes of the spectra, i.e., the forward-scattered light intensities as a function of the magnetic detuning, are sensitive to the transverse intensity distribution of the laser beam. Analytical expressions based on a semiclassical theory are derived and the calculated results on the ring structures and the spectra are compared with the experimental results. Good agreement between the calculated and the experimental results are obtained only when the transverse effects are taken into account.