in this paper we examine the absorption and dispersion properties of a weak probe field via electromagnetically induced transparency (eit) in a four-level system. it is shown that under certain condition, using this model, the absorption cancellation is appeared and the medium becomes transparent to the weak probe field. it will be shown that the controlling of absorption and dispersion spectru...

The capabilities and applicability of the radiotracer technique for methodological studies in hydride generation and electrothermal atomic absorption spectrometry are discussed and demonstrated by using several selected examples. It is shown that, for studying chemical and physico-chemical aspects of atomic absorption spectrometric methods, the radiotracer technique is superior to other techniq...

Using x-ray absorption spectroscopy at the Ru-L2,3 edge we reveal that the Ru4+ ions remain in the S=1 spin state across the rare 4d-orbital ordering transition and spin-gap formation. We find using local spin density approximation + Hubbard U band structure calculations that the crystal fields in the low-temperature phase are not strong enough to stabilize the S=0 state. Instead, we identify a...

We describe light scattering from a graphene sheet having a modulated optical conductivity. We show that such modulation enables the excitation of surface plasmon polaritons by an electromagnetic wave impinging at normal incidence. The resulting surface plasmon polaritons are responsible for a substantial increase of electromagnetic radiation absorption by the graphene sheet. The origin of the ...

The channel interference mechanism describes the two-photon absorption process in terms of the relative orientations of different transition dipole moment vectors (TDMVs) in a molecule. Controlling these interferences is a difficult but important task, because it can provide new information about such absorption/emission processes. The present contribution aims to explain the reversal in the na...

A polarized Raman study of nanographite ribbons on a highly oriented pyrolytic graphite substrate is reported. The Raman peak of the nanographite ribbons exhibits an intensity dependence on the light polarization direction relative to the nanographite ribbon axis. This result is due to the quantum confinement of the electrons in the 1D band structure of the nanographite ribbons, combined with t...

In 1934, Wilhelm Woltersdorff demonstrated that the absorption of light in an ultrathin, freestanding film is fundamentally limited to 50%. He concluded that reaching this limit would require a film with a real-valued sheet resistance that is exactly equal to R = η/2 ≈ 188.5Ω/□, where [Formula: see text] is the impedance of free space. This condition can be closely approximated over a wide freq...

Symmetry-resolved x-ray absorption spectroscopy has been first carried out on high-temperature molecules. From the angle-resolved ion yield spectra of CO2 both at room temperature and at 430 degrees C, symmetry-resolved absorption profiles of the C 1s(-1) 2pi(u) and O 1s(-1) 2pi(u) resonances have been extracted for the vibrational ground state molecules and bending-vibration excited ones. The ...