Potential Energy for the CO<sub>2</sub>‐NaCl(100) and the Lateral Adsorbate Interaction

Heidberg, J.; Kampshoff, E.; Schönekäs, O.; Stein, H.; Weiß, Helmut

doi:10.1002/bbpc.19900940208

Cited by 38 publications

(16 citation statements)

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“…Monomer and dimer adsorption was investigated in the first stage of the simulations. The calculated optimum adsorption site of an isolated CO 2 molecule on the KCl(100) substrate surface is very similar to the adsorption geometry found on the NaCl(100) surface: 7,8 The molecular center of mass is located 2.90 Å over the surface in the hollow site between two neighboring Cl À anions, as shown in Figure 8 (molecule A, site 3). The molecule is oriented parallel to the surface plane with the oxygens pointing toward the K þ cations.…”

Section: ' Potential Calculations and Spectrum Simulationsmentioning

confidence: 78%

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Structure of CO₂ Adsorbed on the KCl(100) Surface

et al. 2011

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The structure and dynamics of the adsorbate CO(2)/KCl(100) from a diluted phase to a saturated monolayer have been investigated with He atom scattering (HAS), low-energy electron diffraction (LEED), and polarization dependent infrared spectroscopy (PIRS). Two adsorbate phases with different CO(2) coverage have been found. The low-coverage phase is disordered at temperatures near 80 K and becomes at least partially ordered at lower temperatures, characterized by a (2√2×√2)R45° diffraction pattern. The saturated 2D phase has a high long-range order and exhibits (6√2×√2)R45° symmetry. Its isosteric heat of adsorption is 26 ± 4 kJ mol(-1). According to PIRS, the molecules are oriented nearly parallel to the surface, the average tilt angle in the saturated monolayer phase is 10° with respect to the surface plane. For both phases, structure models are proposed by means of potential calculations. For the saturated monolayer phase, a striped herringbone structure with 12 inequivalent molecules is deduced. The simulation of infrared spectra based on the proposed structures and the vibrational exciton approach gives reasonable agreement between experimental and simulated infrared spectra.

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Section: ' Potential Calculations and Spectrum Simulationsmentioning

confidence: 78%

“…8,15,16,28,29 Because the dipole moment involved with the ν 3 mode of CO 2 is parallel to its molecular axis, direct structural information is obtained in this way. The A s /A p ratio is plotted in Figure 6 as a function of the tilt angle θ of a dipole moment with respect to the surface plane.…”

Section: ' Introductionmentioning

confidence: 99%

Structure of CO₂ Adsorbed on the KCl(100) Surface

et al. 2011

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“…This adsorption system has become the object of many investigations in recent years (9)(10)(11)(12)(13)(14)(15)(16)(17). In our group a two-dimensional phase transition at pressure p,(T) within the adsorbate has been observed on NaCl(100) samples prepared in air (1 1).…”

Section: Introductionmentioning

confidence: 90%

Two-dimensional sublimation of CO₂ on NaCl(100) with molecular reorientation as revealed by polarization infrared spectroscopy

Heidberg¹,

Kampshoff²,

Kühnemuth³

et al. 1994

Can. J. Chem.

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This paper is dedicnted to Professor John C. Polunyi on the occasion of his 65th birthday J. HEIDBERG, E. KAMPSHOFF, R. KUHNEMUTH, and 0. SCHONEKAS. Can. J. Chem. 72, 795 (1994).Two-dimensional sublimation of C 0 2 on NaC1(100), prepared by cleaving a single crystal in situ under ultrahigh vacuum, was observed by polarization Fourier transform infrared spectroscopy. At the transition pressure pl(T) < 1 x lo-'' mbar in the temperature range 45 < T/K < 75 the 2D solid and the ideal 2D lattice gas coexist in a 2D thermodynamic equilibrium.The temperature dependence of the spreading pressure z(T) of the coexisting 2D lattice gas yields the enthalpy of the 2D sublimation AH: D = (3.0 i 0.1) kJImol. In the two-dimensional sublimation reorientation of the C 0 2 molecules takes place; both the polar and the azimuthal molecular angles change.J. HEIDBERG, E. KAMPSHOFF, R. KUHNEMUTH et 0 . SCHONEKAS. Can. J. Chem. 72, 795 (1994). On a observC, par spectroscopie infrarouge i transformation de fourier polarisee, la sublim?tion bi-dimensionnelle du C 0 2 sur du NaCl(100) prCparC par clivage in situ d'un cristal unique sous vide tri's poussi. A la pression de transition p,(T) < 1 x lo-'' mbar dans l'intervalle de tempirature allant de 45 < T/K < 75 le solide 2D et le rCseau 2D gazeux idCal coexistent dans un Cquilibre thermodynamique 2D. L'effet de la tempirature sur 1'Ctalement de la pression z(T) des rCseaux 2D gazeux coexistants donne l'enthalpie de la sublimation 2D AH: D = (3,O i 0,l) kJImol. I1 se produit une rkorientation des molCcules de C 0 2 dans la sublimation bi-dimensionnelle; les deux angles polaire et azimutale changent.[Traduit par la redaction] Introduction In physisorption, the weak interaction between molecules and solids has been studied for many years. A new topic is the stereodynamics of chemical reactions between surface-aligned and oriented physisorbed molecules (1). This paper reports on the thermodynamics of a two-dimensional phase transition with molecular reorientation as revealed by polarization infrared spectroscopy. The system studied is C 0 2 physisorbed on NaC1(100), which can be considered a model for physisorption. It has become important also in geology, in sea spray chemistry, as well as in industrial applications and waste technology. Rock salt in the extended North German salt domes contains, besides the brine inclusions and water from the associated hydrated minerals, primary gases adsorbed on the crystal boundaries or trapped in inclusions. Knowledge of the behaviour of such primary gases as C02, CH4, H20, and HCl is essential when planning the safety aspects for a final repository of radioactive waste in the salt domes (2). To model the behaviour of these simple gases in the salt domes, studies of the gas adsorption on NaCl(100) under well-defined conditions are necessary. Especially those thermodynamic measurements yielding adsorption isotherms, heats of adsorption, and twodimensional phase transitions give insight into the gas-surface interaction. The results can also be used to desc...

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“…(A2.14) Here b^v and b^v are creation and destruction operators for phonons of the vth acoustic branch (one longitudinal with v = I and two transverse ones with v = t) with the wave vector q which obey the dispersion laws ft\,(q) =c v |q| (c; and c, are the longitudinal and transverse sound velocities). The operator x qv is defined by the relation 15) where p is the medium density, V is the volume of the main area, and e^(q) is the phonon polarization unit vector. Provided the group BC is located on a continuum surface, the deformation vector u is given by Eq.…”

Section: X(0)}(e a (T)ep(0)) = G"(t)(f (T)^(0)) (A25)mentioning

confidence: 99%

Back Matter

2002

World Scientific Lecture and Course Notes in Chemistry

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The Hamiltonian function for a system of bound harmonic oscillators is, in the most general form, a sum of two positively definite quadratic forms composed of the particle momentum vectors and the Cartesian projections of particle displacements about equilibrium positions:where m, is the mass of the ith particle; $ denotes the force constants; a, /} are the projections of corresponding vectors on the Cartesian coordinate axes (summation over Greek indices will be indicated explicitly because it appears in the expressions more than twice). The equations of motion for the displacements u" that correspond

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Potential Energy for the CO₂‐NaCl(100) and the Lateral Adsorbate Interaction

Cited by 38 publications

References 10 publications

Structure of CO₂ Adsorbed on the KCl(100) Surface

Structure of CO₂ Adsorbed on the KCl(100) Surface

Two-dimensional sublimation of CO₂ on NaCl(100) with molecular reorientation as revealed by polarization infrared spectroscopy

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Potential Energy for the CO2‐NaCl(100) and the Lateral Adsorbate Interaction

Cited by 38 publications

References 10 publications

Structure of CO2 Adsorbed on the KCl(100) Surface

Structure of CO2 Adsorbed on the KCl(100) Surface

Two-dimensional sublimation of CO2 on NaCl(100) with molecular reorientation as revealed by polarization infrared spectroscopy

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Potential Energy for the CO₂‐NaCl(100) and the Lateral Adsorbate Interaction

Structure of CO₂ Adsorbed on the KCl(100) Surface

Structure of CO₂ Adsorbed on the KCl(100) Surface

Two-dimensional sublimation of CO₂ on NaCl(100) with molecular reorientation as revealed by polarization infrared spectroscopy