Intense interactions of molecules with a short-wavelength electromagnetic radiation field: I. The fundamentals of the nonadiabatic theory

The intense interactions between short-wavelength (SW) electromagnetic radiation with a wavelength λ ≥ 1 Å and intensity up to 10¹⁴ W/cm² and simple and polyatomic molecules are studied with the coherent excitations of high-lying Rydberg and autoionizing states taken into account. The Hamiltonian of a system “molecule + SW radiation” is obtained by using the methods of quantum electrodynamics. Conditions for the applicability of the dipole approximation to describe the interactions of molecules with radiation of the UV, VUV, XUV, and soft X-ray range are found. The fundamentals of the theory of resonance scattering of SW radiation from diatomic, triatomic, and symmetric-and asymmetric-top polyatomic molecules are outlined.     

Resonance radiation in electromagnetic wave scattering by a fast electron in the external magnetic field

The resonance radiation in Compton scattering of an electromagnetic wave by a fast relativistic electron moving in a given magnetic field is investigated with allowance for deceleration by the radiation. A general expression for the electric field of an arbitrarily polarized scattered wave is derived within the framework of small-perturbation theory. It is shown that the resonance peak in the scattering cross-section is caused by the small radiation friction. The dependence of the resonance line width on the characteristic parameters of the problem is examined. The scattering of a given polarized wave is considered, and the degree of linear polarization of the radiated wave under resonance is determined.Institute of Radiophysics and Electronics, Armenian Academy of Sciences, Erevan. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 38, No. 10, pp. 1001–1011, October, 1995.     

X—射线荧光分析散射幂函数法的原理及其应用

本文在较宽在基体原子序数变化范围内研究了非相干散射随基体吸收系数的变化规律,发现存在一种幂函数关系,用射内标法所假定的反比关系仅在较窄的轻元素范围内存在,实验证实了这种理论规律的存在。提出了用康普散射幂函数法校正基体吸收效应的新方法。列举了幂函数法在地质样品中的锶的测定实例,证明了该法在宽的基体组成范围内比传统的散射内标法适应性强。     

Beta decay in a strong electromagnetic field. II

A study is made of the probability and spin-angle correlations of 3 decay in a strong electromagnetic field consisting of a superposition of a magnetic field and a plane monochromatic wave propagating in the direction of the magnetic field. The cases of a weakly varying wave field and cyclotron resonance, which is possible in such a system, are studied.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 88–92, January, 1981.We are grateful to Professor I. M. Ternov and V. R. Khalilov for helpful discussions and assistance.     

Resonance fluorescence spectrum of a three-level atom. II. Numerical results

Numerical computations are presented for the excitation spectra arising from the interaction between a three-level atom in the cascade configuration and a strong electromagnetic field whose frequency mode is initially populated. The excitation spectra are considered when the laser field is at resonance with the equally spaced levels of the atom as well as a function of the detunings. The physical process of optical amplification occurs without population inversion and it is more pronounced when the laser field is detuned than when it is at resonance. The shapes of the spectral lines for a number of side-bands are of the absorption-amplification type rather than that of the absorption one. In the presence of detunings as well as in the cooperative two-photon cascade process, the resulting spectra are far more complicated than those occuring at resonance. Results of numerical calculations for a wide range of Rabi frequencies and detunings are presented graphically.     

Interaction of a high-temperature plasma with electromagnetic radiation in a gravitational field

The linearized general-relativistic kinetic equation is used to study the interaction of highfrequency electromagnetic radiation with a fully ionized plasma in a gravitational field;, the pseudotensors of the complex conductivity, permittivity, and absorption of energy are constructed.     

Absorption of electromagnetic radiation in systems with orientational interactions

Absorption of electromagnetic radiation in ordered ferroelectric and antiferro-electric systems in external electrical fields has been investigated by means of Monte Carlo method. The dependences of the areas of the hysteresis curves on the frequency of the field have been calculated. At the resonance frequency, there is a maximum of the area of the hysteresis curve; the position of this maximum depends weakly on the temperature and the constant of intra- and interchain inte-ractions, and its height increases with decreasing temperature and increasing the interaction energy between molecules.     

Intense nonlinear magnetic dipole radiation at optical frequencies: molecular scattering in a dielectric liquid

We report white-light generation and intense linear scattering from magnetic dipoles established by the time-varying magnetic flux of an incident light field in a dielectric medium. Large magnetic response is very unexpected at optical frequencies, and should lead to the discovery of new magneto-optical phenomena and the realization of low-loss homogeneous optical media with negative refractive indices.     

Resonance scattering of electromagnetic waves from a rectangular groove on a metallic mirror

Scattering diagrams, calculated from a rigorous theory, are presented for wavelengths comparable to the magnitude of the groove shape parameters.     

Gravitational radiation of Island systems with an electromagnetic field

A study is made of the gravitational radiation of a system of bounded sources in the presence of an electromagnetic field. A class of frames of reference-analogs of inertial frames in flat space-is introduced on the basis of the criterion proposed by Dozmorov. Expressions are obtained for the total energy of such systems and the flux of gravitational radiation.     

Electron scattering by molecules II. Experimental methods and data

Experimental techniques for measuring electron-molecule collision cross sections are briefly summarized. A survey of the available experimental cross section data is presented. The emphasis here is on elastic scattering, rotational, vibrational and electronic excitations, total electron scattering, and momentum transfer in the few eV to few hundred eV impact energy range. Reference is made to works concerned with high energy electron scattering, innershell and multi-electron excitations, coincidence methods and electron scattering in laser fields.     

Refocusing and locating effect of fluorescence scattering field

Optical imaging deep inside scattering medium has always been one of the challenges in the field of bioimaging, which significantly drawbacks the employment of con-focal microscopy system. Although a variety of feedback techniques, such as acoustic or nonlinear fluorescence-based schemes have realized the refocusing of the coherent light, the problems of non-invasively refocusing and locating of linearly-excited fluorescent beads inside the scattering medium have not been thoroughly explored. In this paper, we linearly excited the fluorescent beads inside a scattering medium by using our homemade optical con-focal system, collected the fluorescence scattering light as the optimized target, and established a theoretical model of target contrast enhancement, which is consistent with the experimental data. By improving both the cost function and variation rate within the genetic algorithm, we could refocus the fluorescence scattering field while improving the contrast enhancement factor to 12.8 dB. Then, the positions of the fluorescent beads are reconstructed by sub-pixel accuracy centroid localization algorithm, and the corresponding error is no more than 4.2 μ with several fluorescent beads within the field of view. Finally, the main factors such as the number of fluorescent beads, the thickness of the scattering medium, the modulating parameter, the experimental noise and the system long-term stability are analyzed and discussed in detail. This study proves the feasibility of reconstructing fluorescent labeled cells inside biological tissues, which provides certain reference value for deep imaging of biological tissues.     

Scattering of atoms and molecules by an electromagnetic field

The scattering of atoms and molecules by the force of stimulated light pressure appearing in a standing wave is considered. It is shown that short (10^-8s) light pulses of tunable lasers can deviate resonance atoms through an angle of about 5°. A high selectivity of scattering is retained in a standing wave even in conditions of great saturation. Therefore the considered effect can be used for the separation of isotopes.     

Generation of a continuum and stimulated Raman scattering harmonics during scattering of electromagnetic radiation of relativistic intensity

A theory of the propagation instability of plane, monochromatic, circularly polarized electromagnetic waves of relativistic intensity in matter is developed for a spatially three-dimensional geometry including arbitrary polarization of the scattered radiation. Harmonic generation owing to striction and relativistic nonlinearity is examined, as well as scattering owing to electron recoil, the decay instability of the harmonics with formation of scattered electromagnetic waves (Stokes components of the stimulated Raman scattering and plasmons), the interaction of electromagnetic waves in the plasma (antistokes stimulated Raman scattering), and the generation of a radiative continuum. The transition of the three-dimensional theory to a one-dimensional problem in the nonrelativistic limit is discussed. Zh. éksp. Teor. Fiz. 113, 2034–2046 (June 1998)     

Spectrum of stationary electromagnetic radiation in a static gravitational field

From the equation of continuity, an equation is derived for the change in the spectrum of radiation stationary in a static gravitational field, as measured by local observers in their proper frame. It is shown that an isotropic solution always exists in which the energy density per unit frequency interval is ³ times an arbitrary function of .     

Vacuum generation of electromagnetic radiation by a variable gravitational field

Generation of photons in a curved space-time due to polarization of the electron-positron vacuum is considered: R 2. A general expression for the number of photon pairs is obtained, and the limits of its applicability are discussed.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 9–12, March, 1987.