Optics and Spectroscopy最新文献

The laser generation characteristics of microdisc lasers with optically coupled waveguide operating in continuous wave mode at elevated temperatures are investigated. Laser generation and waveguide effect at temperatures up to 92.5°C were demonstrated. The measured characteristic temperature of microlasers was 65 K in the range of 25–92.5°C.

The paper presents a technique for broadband two-dimensional infrared spectroscopy with signal detection in visible range by nonlinear chirped-pulse upconversion. This approach helps to avoid direct measurement of the mid-infrared signal that requires cryogenic technology, and instead uses low-cost high-sensitivity multichannel silicon linear arrays. This leads to a reduction by two orders of magnitude of the measurement time of a single two-dimensional spectrum, which makes it possible to observe the fast dynamics of complex molecular compounds. The use of a quasi-phase-cycling achieved by sub-cycle delay modulation suppresses scattering background by almost two orders of magnitude and increases the measurement speed twice compared to optical chopping. Numerical simulation using the density matrix formalism and analysis of its evolution based on the solution of the Bloch–Redfield equation effectively reproduces the features of the two-dimensional infrared spectrum of inorganic octacarbonyl dicobalt compound.

Observation of molecular optomechanical effects is complicated by the need to localize electromagnetic energy in metal gaps about 1 nm in size. We propose to use a nanocavity with an epsilon-near-zero medium so that the conditions required for optomechanical coupling are less stringent. In this work, we simulate the enhancement of Raman scattering depending on the permittivity of the material and the polarization of the near field of the nanoparticle. It is shown that when the real part of dielectric permittivity close to zero, Raman scattering demonstrates an additional enhancement.

The effect of the electron-rotational interaction induced by an external magnetic field on the values of Lande g-factors is systematically investigated within the quantum mechanical model of coupled radial Schredinger equations for locally and regularly perturbed electronic-vibrational-rotational (rovibronic) levels of nonadiabatically coupled X ²Σ⁺, A²Π and B²Σ⁺ states of the CN radical, whose isotopomers are of persistent astronomical interest due to their wide use in optical diagnostics of various regions of the interstellar and near-stellar medium.

In this work we present results of numerical modeling of a ZGDC polarization splitter based on SiN thin films. The magnitude of the interference is –15 dB for the TM-mode and –10.4 dB for TE-mode. The transmission coefficient is 43%.

We introduce a strategy to develop multiple-phase structure of inorganic lead halide perovskite CsPbBr₃. The method is based on local optical heating, which allows the creation of strong temperature gradients. Using Raman spectroscopy, it was determined that such gradients induce a distribution of phase transitions within the perovskite crystal. We show that such gradients lead to perovskite multiple-phase structure.

A non-empirical relativistic calculation of the potential energy curve of the ground X ¹Σ⁺ state of the carbon monoxide (CO) molecule in the internuclear distances range R_AB ∈ [0.5, 30.0] a.u. is performed. The calculation is carried out by the multireference configuration-interaction method in the basis of the Dirac–Fock–Sturm orbitals. For the entire specified range of distances, multi-electron quantum-electrodynamic corrections to the CO energy are calculated by the method of the model Lamb shift operator. The contributions of the quantum electrodynamic corrections to the value of the equilibrium internuclear distance (R_{{AB}}^{e}), the dissociation energy D_e and the vibrational constant ω_e of the CO molecule are obtained.

The contributions of additional Fe-binding sites and heme iron to the experimental spectrum of urea-influenced hemoglobin were evaluated based on theoretical analysis of X-ray absorption spectra. The theoretical Fe K-edge X-ray absorption spectra were calculated for structural models of the supposed additional Fe binding sites and heme. Linear combination fit of theoretical spectra showed that in treated hemoglobin iron ions are more likely to be in the additional Fe-binding sites, which is surrounded by the following amino acids: cysteine-93, histidine-146, and asparagine-94 (Cys93, His 146, Asp 94).

A new effective dipole moment model for the (XY₂ symmetry) molecule in a doublet electronic state is derived that includes (as special cases) all currently known models of effective dipole moment for such type molecules, and allows, at the same time, to take into account an influence of spin-rotation interactions on the effective dipole moment operator which were not taken into account in the preceding studies.

A decrease in the gain of the active medium of a nuclear-pumped excimer laser has been experimentally discovered at the B–X- and C–A-transitions of the XeCl* molecule (308, 352 nm), when the Ar‒Xe–CCl₄ medium is pumped with mixed gamma-neutron radiation nuclear reactor. The effect is due to the quenching effect of secondary electrons formed in the active medium of an excimer laser under the influence of instantaneous gamma radiation. The effect increases significantly with increasing gamma radiation flux density, and the loss coefficient can reach values of ~10^–2–2 × 10^–2 cm^–1.