Trapping effects on the vibration-inversion-rotation motions of an ammonia molecule encapsulated in C60_{60} fullerene molecule

The infrared bar-spectrum of a single ammonia molecule encapsulated in nano-cage C$_{60}$ fullerene molecule is modelled using the site inclusion model successfully applied to analyze spectra of CO$_2$ isotopologues isolated in rare gas matrix. Calculations show that NH$_3$ can rotate freely on a sphere of radius 0.184 $\text{\AA}$ around the site centre of the nano-cage and spin freely about its C$_3$ symmetry axis. In the static field inside the cage degenerate $\nu_3$ and $\nu_4$ vibrational modes are blue shifted and split. When dynamic coupling with translational motion is considered, the spectral signature of the $\nu_2$ mode is modified with a higher hindering barrier (2451 cm$^{-1}$), an effective reduced mass (6.569 g.mol$^{-1}$) and a longer tunneling time (55594 ps) for the fundamental level compared to gas-phase values (2047 cm$^{-1}$), (2.563 g.mol$^{-1}$) and (20.85 ps). As a result this mode is red shifted. Moreover, simulation shows that the changes in the bar-spectrum of the latter mode can be used to probe the temperature of the surrounding media in which fullerene is observed

Van't Hoff law for temperature dependent Langmuir constants in clathrate hydrate nanocavities

This work gives a van't Hoff law expression of Langmuir constants of different species for determining their occupancy in the nanocavities of clathrate hydrates. The van't Hoff law's parameters are derived from a fit with Langmuir constants calculated using a pairwise site-site interaction potential to model the anisotropic potential environment in the cavities, as a function of temperature. The parameters can be used for calculating clathrates compositions. Results are given for nineteen gas species trapped in the small and large cavities of structure types I and II [1]. The accuracy of this approach is based on a comparison with available experimental data for ethane and cyclo- propane clathrate hydrates. The numerical method applied in this work, was recently validated from a comparison with the spherical cell method based on analytical considerations [1]Comment: 2 figure

Vector potential quantization and the photon wave-particle representation

5th International Conference on Mathematical Modeling in Physical Sciences (IC-MSquare 2016)International audienceThe quantization procedure of the vector potential is enhanced at a single photon state revealing the possibility for a simultaneous representation of the wave-particle nature of the photon. Its relationship to the quantum vacuum results naturally. A vector potential amplitude operator is defined showing the parallelism with the Hamiltonian of a massless particle. It is further shown that the quantized vector potential satisfies both the wave propagation equation and a linear time-dependent Schrödinger-like equation

Spectroscopic Ellipsometry Study of Spark Plasma Sintered Nano Silver

International audienceSpark Plasma Sintered (SPS) silver layers were studied by Spectroscopic Ellipsometry (SE) using an M-2000V spectroscopic ellipsometer from J. A. Woollam Co., Inc. which operate in rotating compensator mod

Preface

International audienceThis book is dedicated to the application of the different theoretical models described in Volume 1 to identify the near-, mid- and far-infrared spectra of linear and nonlinear triatomic molecules in gaseous phase or subjected to environmental constraints, useful for the study of environmental sciences, planetology and astrophysics.The Van Vleck contact transformation method, described in Volume 1, is applied in the calculation and analysis of IR transitions between vibration–rotation energy levels. The extended Lakhlifi–Dahoo substitution model is used in the framework of Liouville’s formalism and the line profiles of triatomic molecules and their isotopologues subjected to environmental constraints are calculated by applying the cumulant expansion.The applications presented in this book show how interactions at the molecular level modify the infrared spectra of triatomics trapped in a nano-cage (substitution site of a rare gas matrix, clathrate, fullerene, zeolite) or adsorbed on a surface, and how these interactions may be used to identify the characteristics of the perturbing environment

Volume 3: Infrared Spectroscopy of Symmetric and Spherical Top Molecules for Space Observation 1

International audienceThis book is dedicated to the description and application of various different theoretical models to identify the near and mid-infrared spectra of symmetric and spherical top molecules in their gaseous form.Theoretical models based on the use of group theory are applied to rigid and non-rigid molecules, characterized by the phenomenon of tunneling and large amplitude motions. The calculation of vibration-rotation energy levels and the analysis of infrared transitions are applied to molecules of ammonia (NH3) and methane (CH4). The applications show how interactions at the molecular scale modify the near and mid-infrared spectra of isolated molecules, under the influence of the pressure of a nano-cage (the substitution site of a rare gas matrix, clathrate, fullerene or zeolite) or a surface, and allow us to identify the characteristics of the perturbing environment.This book provides valuable support for teachers and researchers but is also intended for engineering students, working research engineers and Masters and doctorate students

Local mean field approximation applied to a 3D spin crossover nanoparticles configuration: free energy analysis of the relative stability of the stationary states

9th International Conference on Mathematical Modeling in Physical Sciences (IC-MSQUARE) 2020 7-10 September 2020, Tinos island, GreeceInternational audienceThe local mean field approximation is applied to an inhomogeneous 3D spin crossover (SCO) nanoparticle configuration with a special focus on its systemic effect on molecules which are localized in the bulk, at the corner, at the edge and at the surface. The matrix effect at the surface is introduced through a specific interaction term, L. The partition function for each region allows the determination of the total free-energy F from which the stability of each configuration is analyzed through thermodynamic considerations. 1.Introduction Fe(II) Spin-crossover (SCO) shows a particular first-order phase transition, with thermal hysteresis [1-5] that is mediated between two spin states, Low-Spin (LS) with degeneracy g LS , stable at low temperatures and High-Spin (HS) with degeneracy g HS (> g LS), stable at high temperatures. Between two temperatures, namely termed T down and T up a SCO molecule can be in one of these two states depending on its thermal history. This "bi-stable" character is the result of the competition between the ligand field energy acting on each spin-state and the elastic interactions between the molecules. 2. Model In the framework of the Ising-like model [6-11] each SCO molecule is described by a two-level fictitious spin having two eigenvalues and , respectively associated with the HS and LS states. The total Hamiltonian of a system of molecules, taking into account the short (J)-and long-range (G) interactions, as well as the matrix effect (L), is expressed as: where g = g HS /g LS , is the energy difference between the (HS) and (LS) states, T is the absolute temperature, is the Boltzmann constant, and M is the total number of molecules located at the surface. In this contribution, the local mean-field approximation (LMFA) [12] which consists in replacing the spin state of each neighbor by its mean value is applied. Accordingly, the short (J)-and the long (G) range interactions are replaced by only one coupling interaction Γ. The global Hamiltonian of the system can then be rewritten as follows: (1

Spectroscopie infrarouge de molécules diatomiques pour l’observation spatiale, Volume 1

International audienceCet ouvrage décrit les méthodes théoriques qui sont mises en oeuvre dans le cadre de recherches fondamentales pour interpréter les spectres de molécules diatomiques observées dans le domaine infrarouge lorsque ces molécules sont soumises à un environnement où la température et la pression modifient leurs spectres infrarouges en phase gazeuse ou dans des nanocages.Il présente les modèles théoriques qui ont été développés pour étudier la modification des spectres infrarouges des diatomiques sous l’effet de la pression, l’élargissement du profil de raie, le déplacement des centres de bandes et la modification du spectre rovibrationnel dans les nanocages ou sur des surfaces.Cet ouvrage s’adresse aux étudiants de master ou de doctorat, aux enseignants, chercheurs, astronomes et astrophysiciens qui analysent les données correspondant à l’interaction du rayonnement électromagnétique avec la matière dans le domaine de l’infrarouge afin d’identifier les espèces chimiques et leurs environnements

Vector potential quantization and the photon intrinsic electromagnetic properties towards nondestructive photon detection

International audienceWe employ here the enhancement of the vector potential amplitude quantization at a singlephoton state. The analysis of the general solution of the vector potential, obtained by resolvingMaxwell's equations, implies that the amplitude is proportional to the angular frequency. Thephoton vector potential function αkλ(r,t) can be written in the plane wave representationsatisfying the classical wave propagation equation, Schrödinger's equation for the energy withthe relativistic massless field Hamiltonian and a linear time-dependent equation for the vectorpotential amplitude operator. Thus, the vector potential αkλ(r,t) with the quantized amplitudemay play the role of a real wave function for the photon in a nonlocal representation that can besuitably normalized. We then deduce that the amplitudes of the electric and magnetic fields,respectively, of a single free photon are proportional to the square of the angular frequency. Thismight open perspectives for the development of nondestructive photon detection methods basedon the influence of the electric and/or magnetic fields of photons on the energy levels of atomsand molecules