Modification of Nanodiamonds by Xenon Implantation: A Molecular Dynamics Study

Xenon implantation into nanodiamonds is studied using molecular dynamics. The nanodiamonds range in size from 2-10 nm and the primary knock-on (PKA) energy extends up to 40 keV. For small nanodiamonds an energy-window effect occurs in which PKA energies of around 6 keV destroy the nanodiamond, while in larger nanodiamonds the radiation cascade is increasingly similar to those in bulk material. Destruction of the small nanodiamonds occurs due to thermal annealing associated with the small size of the particles and the absence of a heat-loss path. Simulations are also performed for a range of impact parameters, and for a series of double-nanodiamond systems in which a heat-loss path is present. The latter show that the thermal shock caused by the impact occurs on the timescale of a few picoseconds. These findings are relevant to ion-beam modification of nanoparticles by noble gases as well as meteoritic studies where implantation is proposed as the mechanism for xenon incorporation in pre-solar nanodiamonds

Absorption in One-Dimensional Lossy Photonic Crystal

In this work we have obtained the absorption property in one-dimensional (1D) defective lossy photonic crystals (PCs) composed of double-negative (DNG) and double-positive materials by using transfer matrix method . The considered asymmetric geometric structures contain a defect structure at the center of the host crystal as a photonic-quantum-well (PQW) with two different types of DNG layers. This study investigates the effect of the stack number of the bilayers PQW defect on the number, position, and the rate of the absorption of anti-resonant modes for both types of the DNG defect. The results show that these factors of the anti-resonant modes depend on the types of the DNG metamaterial corresponding to the defect layers. Accordingly, by changing the types of PQW defect, the anti-resonant modes are red-shifted or blue-shifted as a function of the stack number of PQW. Furthermore, the effect of loss factors on the rate of absorption is examined for the two different types of PQW. The results can present helpful information for designing new types of narrowband and multichannel filters at the microwave