Dating of hot springs at Attri,Tarabalo and Athmalik sites in Odisha,India using radiocarbon technique

Journal of Radioanalytical and Nuclear Chemistry - In this study environmental radioisotopes of water (3H and 14C) were used to determine the residence time of thermal waters. The temperature of...     

Ferromagnetism Exhibited by Nanoparticles of Noble Metals

Gold nanoparticles with average diameters in the range 2.5–15 nm, prepared at the organic/aqueous interface by using tetrakis(hydroxymethyl)phosphonium chloride (THPC) as reducing agent, exhibit ferromagnetism whereby the saturation magnetization M_S increases with decreasing diameter and varies linearly with the fraction of surface atoms. The value of M_S is higher when the particles are present as a film instead of as a sol. Capping with strongly interacting ligands such as alkane thiols results in a higher M_S value, which varies with the strength of the metal–sulfur bond. Ferromagnetism is also found in Pt and Ag nanoparticles prepared as sols, and the M_S values vary as Pt>Au>Ag. A careful study of the temperature variation of the magnetization of Au nanoparticles, along with certain other observations, suggests that small bare nanoparticles of noble metals could indeed possess ferromagnetism, albeit weak, which is accentuated in the presence of capping agents, specially alkane thiols which form strong metal–sulfur bonds.     

Light-matter interactions via the exact factorization approach

The exact factorization approach, originally developed for electron-nuclear dynamics, is extended to light-matter interactions within the dipole approximation. This allows for a Schrödinger equation for the photonic wavefunction, in which the potential contains exactly the effects on the photon field of its coupling to matter. We illustrate the formalism and potential for a two-level system representing the matter, coupled to an infinite number of photon modes in the Wigner-Weisskopf approximation, as well as to a single mode with various coupling strengths. Significant differences are found with the potential used in conventional approaches, especially for strong couplings. We discuss how our exact factorization approach for light-matter interactions can be used as a guideline to develop semiclassical trajectory methods for efficient simulations of light-matter dynamics.