Resonant Compton Scattering of Two Photons by a Multiply Charged Atomic Ion

JETP Letters - A pronounced K α1,2 X-ray emission spectrum is theoretically predicted for the resonant inelastic scattering of two photons in the energy region near the 1s shell ionization...     

Doubly-Excited States of Two-Electron Systems in Lorentzian Astrophysical Plasmas

The nonthermal effects on the doubly-excited resonance states of two-electron positive ions are investigated in Lorentzian astrophysical plasma environments using highly correlated Hylleraas-type wave functions in the framework of the stabilization method. Resonance parameters (resonance position and width) for Li⁺,  Be²⁺ and B³⁺ are reported for the first time as functions of the spectral index and plasma parameter.     

Bremsstrahlung in Resonant Compton Scattering of a Photon by an Atom

Journal of Experimental and Theoretical Physics - An analytic equation for the anomalous magnetic moment of an electron in a static magnetic field in the topologically massive 2D electrodynamics is...     

Resonant Scattering of Picosecond Laser Pulses by Atoms in Alkali Metal Vapors

Resonant scattering of ultrashort laser pulses (ULPs) in the vicinity of spectral doublets in monatomic lithium and sodium vapors is studied theoretically. The scattering probability over the entire time of pulse action is calculated as a function of various parameters of the problem (carrier frequency and ULP duration, as well as vapor pressure and temperature). It is shown that the dependence of the total scattering probability on the pulse duration is generally nonlinear by nature.     

Bremsstrahlung Effect at Resonant Compton Scattering of a Photon by a Multielectron Atom

JETP Letters - The leading role of the bremsstrahlung at resonant Compton scattering of a hard X-ray photon by a multielectron atom has been theoretically predicted. This result can be important in...     

Lowering of the Populations of Excited Hydrogen and Helium Atoms in Plasmas Irradiated by a Laser Beam

The populations of excited hydrogen and helium atoms in non-L.T.E. plasmas have been calculated for two different physical situations, namely (i) no external radiation field present, and (ii) strong superposed radiation originating from a CO₂, Ruby or Argon Ion Laser. The radiation field intervenes in the collisional-radiative model via two new terms: Photoionization and stimulated recombination induced by the Laser radiation field. The solutions of the rate equations yield a lowering of the populations when a plasma is irradiated by a Laser beam. The lowering is different for cold recombining and hot diffusion-dominated plasmas. At high radiation densities a saturation effect occurs, since the photoionization rate becomes equal to the rate of stimulated recombination. Measurements of the populations of excited H and He atoms in a glow discharge irradiated by a CO₂ Laser beam of power density 10⁵ W/cm² are in broad agreement with the theoretical predictions.     

Compton Scattering and Induced Compton Scattering in a Constant Electromagnetic Field

The spectral and angular distributions for the Compton effect in a constant electro-magnetic field are obtained. The possibility of the existence of the induced Compton scattering in an external field (i.e. two-photon emission, one of the two photons being induced by the incident wave) is demonstrated. In the case of a constant magnetic field the deviation from the Klein-Nishina formula of the obtained distribution for the Compton effect as well as the behaviour of the distribution for the induced Compton effect are discussed. The optimal region of the parameters for the possible experimental test of these effects is given.     

Pressure Ionization of Atoms in Plasmas

It is shown that the main physical reason leading to the ionization of the atoms in plasmas at high densities (pressures) is the Pauli exclusion principle for the electrons which is responsible for the big spatial extension of atoms. Especially for the example of hydrogen the theory is extended to include those effects. Spatial and energetic variants for the definition of the species atom are discussed. The quantum theory of bound states in plasmas is compared with the classical theory of ion association in electrolytes.     

Resonant Scattering of Muonic Hydrogen Atoms and Dynamics of the Muonic Molecular Complex

Resonant scattering of muonic hydrogen atoms via back decay of the molecular complex, a key process in the understanding of epithermal muonic molecular formation, is analyzed. The limitations of the effective rate approximation are discussed and the importance of the explicit treatment of the back decay is stressed. An expression of the energy distribution for the back-decayed atoms is given. This revised version was published online in August 2006 with corrections to the Cover Date.     

Positron-Impact Excitation of Hydrogen Atoms in Debye Plasmas

The positron-impact excitation of hydrogen atoms embedded in plasma environments is investigated using the close-coupling approximation from the low to intermediate energy region without including any positronium formation channel, and the excitation cross sections for 1s→2s, 1s→2p and 2s→2p processes are calculated in a wide Debye parameter range. The screening interactions, described by the Debye-Hückel model, decrease the coupling matrix elements, resulting in the reduction of the excitation cross sections from a few percent to one magnitude of ten. This will alter remarkably the spectroscopy of hydrogen in intensity and position, which should be considered in the simulation and diagnostics under some specific plasma conditions.     

Elastic Scattering of Two Photons by a Multicharged Atomic Ion

The elastic scattering of two X-ray photons by a multicharged atomic ion has been studied theoretically. A pronounced resonance structure and strong angular anisotropy of differential scattering cross section have been predicted in the energy range of a scattered photon from ?ω–I_1s to ?ω+I_1s (where is the energy of the incident photon and is the ionization energy threshold of the shell of the ion). The absolute value of the observed cross section has been quantitatively estimated.     

Resonant Raman Scattering by excitonic polaritons in semiconductors

We report results on Resonant Raman Scattering (RRS) mediated by excitonic polaritons in a high-purity semiconductor (CdTe) at low temperatures. For the first time ingoing and outgoing resonances at the n = 1, 2, 3 exciton states are detected on the one and two LO-phonon RRS. The transformation at resonance of sharp Raman peaks into well-thermalized exciton luminescence bands is observed for every ingoing, outgoing or intermediate state resonance.     

Effect of Quadrupole Emission in Scattering of Two Photons by an Atom

JETP Letters - A pronounced quadrupole emission effect is theoretically predicted in terms of the contact interaction operator in resonant inelastic scattering of two X-ray photons near the...     

Resonant Auger Scattering by Attosecond X-Ray Pulses

As x-ray probe pulses approach the subfemtosecond range, conventional x-ray photoelectron spectroscopy(XPS) is expected to experience a reduction in spectral resolution due to the effects of the pulse broadening.However, in the case of resonant x-ray photoemission, also known as resonant Auger scattering(RAS), the spectroscopic technique maintains spectral resolution when an x-ray pulse is precisely tuned to a core-excited state. We present theoretical simulations of XPS and RAS spectra on a sho...     

Experiment on Gamma Ray Generation by Laser Compton Scattering

A gamma ray generation facility was developed through laser Compton scattering on an electron beam storage ring, for the purpose of researching nuclear transmutation. Theoretical analysis on gamma ray yield and energy spectrum was performed, as well as EGS4 simulation code was employed to simulate the interaction of gamma ray and Ge detector. The acquired experimental results are in agreement with theory.     

Nucleon Compton Scattering in the Perturbative Limit

The paper presents results of perturbative calculations for nucleon Compton scattering. The results are given for the real incoming photon and for the virtual incoming photon.