相关论文: Asymmetric Deviation of the Scattering Cross Secti…
We present a low energy expansion of the Kramers-Heisenberg formula for atomic hydrogen in terms of $(\omega/\omega_l)$, where $\omega_l$ and $\omega$ are the angular frequencies corresponding to the Lyman limit and the incident radiation,…
Damped Ly\alpha\ systems (DLAs) observed in the quasar spectra are characterized by a high neutral hydrogen column density $N_{HI}>2\times 10^{20}{\rm\ cm^{-2}}$. The absorption wing profiles are often fitted using the Voigt function due to…
We consider the elastic scattering of electrons by hydrogen atoms in the presence of a two-color circularly polarized laser field in the domain of moderate intensities below $10^{13}$ W/cm$^2$ and high projectile energies. A hybrid approach…
We study the total cross section and angular distribution in Rayleigh scattering by hydrogen atom in the ground state, within the framework of Dirac relativistic equation and second-order perturbation theory. The relativistic states used…
We present explicit expressions for Rayleigh and Raman scattering cross-sections and phase matrices of the ground $1s$ state hydrogen atom based on the Kramers-Heisenberg dispersion formula. The Rayleigh scattering leaves the hydrogen atom…
The non-relativistic cross section from Rayleigh scattering by hydrogen atoms in the ground state is calculated over a wide range of photon energies ($< 0.8$ keV). Evaluations are performed in terms of the real and imaginary components of…
We present some theoretical predictions concerning the amplitude and magnetic sensitivity of the linear polarization signals produced by scattering processes in the hydrogen Ly-alpha line of the solar transition region. To this end, we have…
Probing the magnetism of the upper solar chromosphere requires measuring and modeling the scattering polarization produced by anisotropic radiation pumping in UV spectral lines. Here we apply PORTA (a novel radiative transfer code) to…
We investigate the escape of Ly$\beta$ from emission nebulae with a significant population of excited hydrogen atoms in the level $n=2$, rendering them optically thick in H$\alpha$. The transfer of Ly$\beta$ line photons in these optically…
A crucial physical quantity in determining the 21-cm signal during cosmic dawn is the inhomogeneous background of Ly$\alpha$ photons originating from the first galaxies. As these photons travel through the intergalactic medium, their…
It is shown that taking into account a recoil for radiation scattering in the Ly-alpha line can lead to a noticable acceleration of primordial hydrogen recombination. Thus for LambdaCDM model a decrease of ionization degree exceeds 1% for…
Recent cosmological observations indicate that the reionized universe may have started at around z=6, where a significant suppression around Ly alpha has been observed from the neutral intergalactic medium. The associated neutral hydrogen…
We used HST/STIS to obtain the spectrum of molecular hydrogen associated with the damped Ly$\alpha$ system at $z_{\rm abs}=1.7765$ toward the quasar Q1331+170 at $z_{\rm em}=2.084$. Strong ${\rm H}_2$ absorption was detected, with a total…
The asymmetry of the natural line profile for transitions in hydrogen-like atoms is evaluated within a QED framework. For the Lyman-alpha $1s-2p$ absorption transition in neutral hydrogen this asymmetry results in an additional energy shift…
We develop an approach to describing coherent Compton scattering of photons in the keV energy range from hydrogen and helium atoms based on a relativistic version of the AA-approximation within the standard perturbative S-matrix formalism.…
The optical theorem relates the total scattering cross-section of a given structure with its forward scattering, but does not impose any restrictions on other directions. Strong backward-forward asymmetry in scattering could be achieved by…
The recently derived distributions for the scattering-matrix elements in quantum chaotic systems are not accessible in the majority of experiments, whereas the cross sections are. We analytically compute distributions for the off-diagonal…
Although the spectral lines of hydrogen contain valuable information on the physical properties of a variety of astrophysical plasmas, including the upper solar chromosphere, relatively little is known about their scattering polarization…
Deep inelastic neutron scattering experiments using indirect time-of-flight spectrometers have reported a smaller cross section for the hydrogen atom than expected from conventional scattering theory. Typically, at large momentum transfers,…
We introduce a nonlinear photonic system that enables asymmetric localization and unidirectional transfer of an electromagnetic wave through the second harmonic generation process. Our proposed scattering setup consists of a…