One-atom-thick reflectors for surface plasmon polariton surface waves on graphene

Inspired by its analog from classic optics, we introduce one-atom-thick reflectors for infrared (IR) surface plasmon polaritons (SPP) surface waves based on graphene. Using numerical simulations, we first present the simple case of one-atom-thick straight-line mirror and then show how a one-atom-thick parabolic reflector (mirror) can be envisioned for focusing guided SPP waves on the graphene.     

The Selfconsistent Pauli Equation

 We deal with consistent first order non-relativistic corrections (i.e. in the small parameter , where c is the speed of light) of the Dirac–Maxwell system. We discuss a selfconsistent modeling of the Pauli equation as the O(ɛ) approximation of the Dirac equation. We suggest a coupling to the “magnetostatic”O(ɛ) approximation of the Maxwell equations consisting of Poisson equations for the four components of the potential. We sketch the semiclassical/nonrelativistic limits of this model.     

DFT (density functional theory) studies on cycloisomerization of 15–membered triazatriacetylenic macrocycle

The mechanism as well the stereochemistry of cascade cycloisomerization of 15–membered triazatriacetylenic macrocycle was investigated theoretically by using M062X/6–31+G(d,p) and M062X/LANL2DZ calculations. The results showed that the mechanism and outcome of the reaction depended on the absence and presence of a transition metal catalyst. So that, in thermal-induced condition, the reaction had to experience several suprafacial concerted reactions including Ene-reaction (DG^#=35.38 kcal/mol), Diels–Alder cycloaddition (DG^# = 17.16 kcal/mol), and sigmatropic H-shift rearrangement (DG^# = 56.21 kcal/mol) to produce diastereoselective fused cis–tetracyclic aromatic bearing a pyrrole moiety by following kinetic considerations. Also, the [2+2+2] cycloaddition mechanism was neglected in thermal–induced conditions because of high activation free Gibbs energy (DG^# = 63.90 kcal/mol). In the presence of palladium catalyst, Pd(0) formed an adduct by coordinating to C = C bonds and decreased the DG^# of the process to 29.58 kcal/mol, and consequently provided a facilitated media for the reaction to follow the [2+2+2] to produce more stable fused tetracyclic benzenoid aromatic by passing through the lower energy barrier.     

A Luminescent Guest@MOF Nanoconfined Composite System for Solid-State Lighting

A series of rhodamine B (RhB) encapsulated zeolitic imidazolate framework-8 (RhB@ZIF-8) composite nanomaterials with different concentrations of guest loadings have been synthesized and characterized in order to investigate their applicability to solid-state white-light-emitting diodes (WLEDs). The nanoconfinement of the rhodamine B dye (guest) in the sodalite cages of ZIF-8 (host) is supported by fluorescence spectroscopic and photodynamic lifetime data. The quantum yield (QY) of the luminescent RhB@ZIF-8 material approaches unity when the guest loading is controlled at a low level: 1 RhB guest per ~7250 cages. We show that the hybrid (luminescent guest) LG@MOF material, obtained by mechanically mixing a suitably high-QY RhB@ZIF-8 red emitter with a green-emitting fluorescein@ZIF-8 “phosphor” with a comparably high QY, could yield a stable, intensity tunable, near-white light emission under specific test conditions described. Our results demonstrate a novel LG@MOF composite system exhibiting a good combination of photophysical properties and photostability, for potential applications in WLEDs, photoswitches, bioimaging and fluorescent sensors.     

Long-Time Instability of the Couette Flow in Low Gevrey Spaces

We prove the instability of the Couette flow if the disturbances is less smooth than the Gevrey space of class 2. This shows that this is the critical regularity for this problem since it was proved in [5] that stability and inviscid damping hold for disturbances which are smoother than the Gevrey space of class 2. A big novelty is that this critical space is due to an instability mechanism which is completely nonlinear and is due to some energy cascade. © 2023 The Authors. Communications on Pure and Applied Mathematics published by Wiley Periodicals LLC.