Nonlinear photoionization of transparent solids: a nonperturbative theory obeying selection rules

We provide a nonperturbative theory for photoionization of transparent solids. By applying a particular steepest-descent method, we derive analytical expressions for the photoionization rate within the two-band structure model, which consistently account for the $selection$ $rules$ related to the parity of the number of absorbed photons ($odd$ or $even$). We demonstrate the crucial role of the interference of the transition amplitudes (saddle-points), which in the semi-classical limit, can be interpreted in terms of interfering quantum trajectories. Keldysh's foundational work of laser physics [Sov. Phys. JETP 20, 1307 (1965)] disregarded this interference, resulting in the violation of $selection$ $rules$. We provide an improved Keldysh photoionization theory and show its excellent agreement with measurements for the frequency dependence of the two-photon absorption and nonlinear refractive index coefficients in dielectrics

Relationships between forest-stand parameters and Sentinel-2 spectral reflectance in the Central Russian forest-steppe

The article presents results of analysis of the relationships between forest-stand parameters (age, height, growing stock volume) and Sentinel-2 spectral reflectance in the Central Russian forest-stepp

Spatiotemporal spectral-response assessment of the forest cover of small dry valleys in the Central Russian forest-steppe

Results of assessment are presented for the relationship between the forest cover of small dry valleys and their spectral response through analysis of object data in the forest-steppe natural zone of the Central Chernozem region of Russia. The SWIR reflectance of small dry valleys is shown to be tightly correlated with the percentage of forest cove

Integration strategies of academic research and environmental education

The paper deals with the prospects of using GIS-technologies and remote sensing ones as the main directions of implementing the innovation project in the sphere of environmental education. The paper suggests new models and technologies in the system of teaching that rely on the obtained experience of implementation of environmental education tasks and integration of modern technologies into ityesБелгородский государственный университе

The Use of Remote Sensing Methods for Studying of the Ancient Greek Land Division System of Tauric Chersonesos on the Mayachnyy Peninsula of the Crimea Peninsula

A detailed analysis of the 1940s archival aerial photographs and a 1966 satellite image, has shown that the earliest land division of the ancient Tauric Chersonesos affected the Sredinnyy Peninsula of the Crimean Peninsula, as well as the territory to the southeast of the fortification on the isthmus of Mayachnyy, which is on the outside the Mayachnyy Peninsul

Post-agrogenic evolution of soils in ancient Greek land use areas in the Herakleian peninsula, southwestern Crimea

The paper examines the regularities of the post-agrogenic evolution of soils of differing age in the Herakleian Peninsula (southwestern Crimea, Ukraine), which developed under conditions of the sub-Mediterranean climate and have been cultivated since ancient timesyesBelgorod State Universit

The light nuclei spin structure from hadronic channels at intermediate energies

The main goal of the investigation of the reaction induced by the polarized deuterons is to establish the nature of 2N and 3N forces, the role of the relativistic effects and nonucleon degrees of freedomyesBelgorod State Universit

The influence of relief on the density of light-forest trees within the small-dry-valley network of uplands in the forest-steppe zone of Eastern Europe

This paper investigates the spatial features of the density of trees in forest-steppe uplands of the East European Plain and its relationship with relief parameters. The Belgorod Region, one of the administrative regions of European Russia, was chosen as a reference for the forest-steppe zone of the plai

Soil-genetic differences of multi-aged fallow lands in an ancient agricultural region of steppe Crimea

The aim of the study was to comparatively analyse the soils of fallow lands of different times near the ancient settlement of the NW Crimea and to identify relict and recent evidence of pedogenesi