The discovery of combination scattering of light in Russia and India

Abstract

The valence band electronic structure of GeSe single crystals has been investigated using angle resolved photoemission spectroscopy (ARPES) and x-ray photoelectron spectroscopy. The experimentally observed bands from ARPES, match qualitatively with our LDA-based band structure calculations along the Γ-Z, Γ-Y and Γ-T symmetry directions. The valence band maximum occurs nearly midway along the Γ-Z direction, at a binding energy of −0.5 eV, substantiating the indirect band gap of GeSe. Non-dispersive features associated with surface states and indirect transitions have been observed. The difference in hybridization of Se and Ge 4p orbitals leads to the variation of dispersion along the three symmetry directions. The predominance of the Se 4p z orbitals, evidenced from theoretical calculations, may be the cause for highly dispersive bands along the Γ-T direction. Detailed electronic structure analysis reveals the significance of the cation-anion 4p orbitals hybridization in the valence band dispersion of IV-VI semiconductors. This is the first comprehensive report of the electronic structure of a GeSe single crystal using ARPES in conjugation with theoretical band structure analysis.

Constraints on a Tidal Charge of the Supermassive Black Hole in M87* with the EHT Observations in April 2017

“…Firstly, the discussion of models in which the evolution of the universe is considered was actually banned, and secondly, G. Gamow, who left the USSR without the permission of the authorities, was considered a traitor and an enemy of the country, and it was extremely dangerous for a Soviet scientist to claim that Gamow's model was confirmed by observations. On the other hand, one of Raman and K. S. Krishnan (now this phenomenon is called the Raman effect) [45] but Soviet researchers submitted their manuscript slightly later than Indian ones since during the period when it was necessary to prepare the article for publication, it turned out that Mandelstam's relative was arrested and sentenced, and only Mandelstam's petitions led to the replacement of the execution with a link [44]. In 1928 Mandelstam and Leontowitsch were among the first authors who considered tunnelling through a potential barrier analyzing properties of solutions of Schrödinger equation [46].…”

“…A nice essay about the Mandelstam's school (in particular, its discovery of combinational scattering in 1928) is presented in[45].…”

Surface-Enhanced Raman Scattering Substrates Based on Self-Assembled PEGylated Gold and Gold–Silver Core–Shell Nanorods

“…Despite the great variety of existing technologies, 11,14,15 most SERS platforms fall into five broad categories: (1) regular metal substrates, fabricated by nanosphere lithography 34 and other lithographic techniques (e.g., refs 16 and 31 and references therein); (2) substrates fabricated by lithographic patterning 35 or multistage transfer printing; 36 (3) "film-over-spheres" platforms, obtained with appropriate nanosized templates; 30,31,37−43 (4) metal nanoparticles (NPs) assembled on silicon, glass, 44−47 silica nanospheres, 48,49 inverse opals, 50 or simply on Whatman filter paper; 51,52 which combine plasmonic NPs with specific Raman reporter organic molecules. 13,18,53 Thanks to the remarkable progress in NP synthesis technologies, 54−56 one of the most simple and cost-effective strategies to manufacture SERS substrates is to fabricate selfassembled nanoparticle films.…”

“…Since the first theoretical prediction and experimental observations in crystals and liquids (February 21 and 27, 1928, respectively), Raman scattering remained a potentially important yet unpractical spectroscopic tool for almost 50 years until the first observations − of the surface-enhanced Raman scattering (SERS) were published and the electromagnetic , and chemical mechanisms of SERS were suggested (for the discussion of the early SERS history, see, e.g., Haynes et al). After these seminal steps, − the annual number of SERS-related papers increased dramatically to about 1500 the past few years .…”