X-ray circular dichroism under reflection from antiferromagnetically coupled multilayers

The fluorescence yield under the Bragg reflection of right and left circular polarized radiation with a wavelength in the vicinity of the FeL _{2, 3} absorption edges from the periodic multilayer [Fe(1.5 nm)/V(1.5 nm)]₁₀ that is characterized by the antiferromagnetic interlayer exchange coupling has been theoretically analyzed in L-MOKE geometry. It has been shown that the largest polarization asymmetry of reflectivity takes place at the ??magnetic?? Bragg reflection, which appears due to the doubling of the magnetic period. The expected occurrence of the dichronic signal in the fluorescence yield by its selective excitation in the layers with the same magnetization direction was confirmed, but the effect is suppressed by the specific behaviour of the standing waves in the strongly absorbing multilayers where the standing wave antinodes are situated in layers with low absorption.     

Determination of the magnetic contribution to the YFe2 susceptibility by means of X-ray resonant magnetic reflectivity

The reflectometry curves of an Nb(4 nm)/YFe₂(40 nm, 〈110〉)/Fe(1.5 nm)/Nb(50 nm) sample measured in the synchrotron radiation of right- and left-handed circular polarization for a set of wavelengths near the Y L _2,3 absorption edges have been used to determine the energy dependences of the component magnitudes for the X-ray susceptibility tensor of YFe₂ near the yttrium absorption edges, including off-diagonal magnetic additives. Our result is in good agreement with the normalized experimental absorption and circular dichroism spectra and their Kramers-Kronig transformations.     

Four-photon polarization spectroscopy of water and its isotopic molecules in the spectral range between 0 and 50 cm<Superscript>–1</Superscript>

By the method of saturation of absorption of counterpropagating light waves, the gas-phase spectrum of SiF₄ is obtained without Doppler broadening of spectral lines. In the frequency range of the generation of a low-pressure CO₂ laser (the 9.4-μm band), multiplets of the superfine structure (associated with tunneling transitions between the states of rotation about the equivalent symmetry axes of the SiF₄ molecule) of the spectrum were observed. Weak satellites were observed in the vicinity of the multiplets. Some of the satellites were interpreted as resonances formed by the collisional transfer of the three-photon Bennett holes and peaks.