'Internal' and 'external' vibrational modes of CO2/NaCl(001) studied by Fourier-transform infrared spectroscopy and helium atom scattering

Heidberg, J.; Kampshoff, E.; Kühnemuth, Ralf; Schönekäs, O.; Lange, Gerrit; Schmicker, D.; Toennies, J. P.; Vollmer, R.; Weiß, Helmut

doi:10.1016/0368-2048(93)80096-5

Cited by 19 publications

(8 citation statements)

References 31 publications

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“…4 Another most valuable tool for investigating the interaction of molecules with well-defined alkali halide surfaces is the elastic and inelastic scattering of atoms and molecules from the surfaces, in particular helium atom beam diffraction and time of flight spectroscopy. 5,6 A wealth of information is available concerning the scattering of H 2 from alkali halides, specifically LiF͑001͒. Inclusion of the quadrupole-ionic lattice interaction in the theory leads to large differences between the diffraction of H 2 in its Jϭ0 and Jϭ1 rotational states.…”

Section: Introductionmentioning

confidence: 99%

Monolayers of ortho-H2, para-H2, para-D2 and normal-H2 adsorbed on NaCl(001) single crystal surfaces

Heidberg

Voßberg

Hustedt

et al. 1999

The Journal of Chemical Physics

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Articles you may be interested inThe structure of N2 adsorbed on the rumpled NaCl(100) surface-A combined LEED and DFT-D study J. Chem. Phys. 137, 174705 (2012); 10.1063/1.4764299The monolayer structure of CO 2 adsorbed on the NaCl(100) single crystal surface: A tensor low-energy electron diffraction analysis A two-dimensional quantum crystal: H 2 on NaCl (100) Experimental and theoretical studies of the monolayer structure of OCS adsorbed on NaCl(001): Coexistence of orientationally inequivalent phases Monolayers of pure ortho-H 2 , para-H 2 , para-D 2 and normal-H 2 adsorbed on NaCl͑001͒ single crystal surfaces were investigated at temperatures Tу10 K and pressures between 1ϫ10 Ϫ10 and 1ϫ10 Ϫ5 mbar by polarization Fourier transform infrared attenuated total internal reflection spectroscopy ͑PIRS-ATR͒. Single induced polarized infrared absorptions of the fundamental vibrational modes of pure (M ϭ͉1͉) ortho-H 2 and para-H 2 , as well as pure (M ϭ͉1͉) para-D 2 and, slightly shifted, in the mixture of normal-H 2 were observed, allowing definite assignments of each. With respect to the gas phase values, the wave numbers were measured to be redshifted by 32.0 and 28.0 cm Ϫ1 for pure (M ϭ͉1͉) ortho-H 2 and para-H 2 . In close agreement with potential calculations, these absorptions were assigned to H 2 molecules adsorbed on the cation sites of the large NaCl͑001͒ terraces, while neither the absorptions associated with H 2 adsorption above defects nor the absorptions of (M ϭ0) H 2 molecules above the anion sites, detected on microcrystallite surfaces at lower temperature, are observed under the conditions set. The present experiments corroborate the fact that the NaCl surface discriminates between the (M ϭ͉1͉) ortho-, (M ϭ0) ortho-and paraspecies. The lateral interactions have no influence on the stable sites and the discrimination, but they contribute by an additional shift of the peak frequencies of about 15%. Moreover, with polarized light, induced transition dipole moments perpendicular to the surface for ortho-H 2 , para-H 2 and para-D 2 were observed, while none parallel to the surface was detected. These results are in accordance with the calculations showing that the s-component of the polarization disappears due to free rotation of the H 2 (D 2 ) molecules in a plane parallel to the surface, while the p-component gives a maximum intensity. The integrated cross sections Ќ were measured and found to have the same order of magnitude: (6Ϯ3)ϫ10 Ϫ22 m/molecule for (M ϭ͉1͉) ortho-H 2 and (4Ϯ2)ϫ10 Ϫ22 m/molecule for para-H 2 within the error limits; the theoretical value is 4.5ϫ10 Ϫ22 m/molecule for both species. Applying the extended Langmuir equation, the difference between the desorption energies (E des ortho ϪE des para ) of (Mϭ͉1͉) ortho-H 2 and para-H 2 adsorbed on the ͑001͒ terraces of NaCl͑film͒ was determined to be 0.6Ϯ0.2 kJ/mol, in agreement with the calculated value ͑0.8 kJ/mol͒. Assuming that the sticking coefficients of (M ϭ͉1͉) ortho-H 2 and para-H 2 are not dependent on temperature between 17 and 30 K,...

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Section: Introductionmentioning

confidence: 99%

Monolayers of ortho-H2, para-H2, para-D2 and normal-H2 adsorbed on NaCl(001) single crystal surfaces

Heidberg

Voßberg

Hustedt

et al. 1999

The Journal of Chemical Physics

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“…CO, CO 2 , water and H 2 physisorbates on MgO were also investigated. [28,[48][49][50][51] Especially in the case of H 2 , the low incident energy of the He atoms was essential, since the adsorption energy was in the range of 20 to 25 meV and the molecules could be desorbed even by He atoms with an energy exceeding 40 meV. MgO is not the only "well-ordered" oxide surface.…”

Section: Why Oxides?mentioning

confidence: 99%

Helium Atom Scattering from Oxide Surfaces

Traeger

2006

ChemPhysChem

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Many experimental methods of surface science employ electrons or photons of considerable incident energy as probe particles. However, insulating surfaces or delicate physisorbed layers may be damaged by these particles and should, therefore, be analyzed with a gentler probe: He atom scattering allows to determine the symmetry of the unit cell and the detection of phase transitions from diffraction measurements as well as the determination of surface and adsorbate vibrations by time-of-flight resolved detection. Herein, the application of He atom scattering to oxide surfaces is demonstrated on the basis of the examples of MgO and ZnO. MgO(001) is a very inert and stable surface, whereas hydrogen atoms are chemisorbed on the mixed-terminated ZnO(1010) and on both polar faces: ZnO(0001) and ZnO(0001). He atom scattering is very sensitive to the presence of hydrogen on surfaces. In addition ZnO reacts with molecules such as water, CO and CO(2). It is demonstrated that in combination with photoelectron spectroscopy and thermal desorption spectroscopy He atom scattering can also contribute to studies of surface chemistry.

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“…For the first attempts we have assumed the translational symmetry pg (with glide planes) which has been reported for the system CO 2 -NaCl(100) [45][46][47]. Recently, simulations based upon the 2D space groups pmg (with glide planes, mirror planes perpendicular to them and two-fold rotation axes) as reported for CO-NaCl(100) [40] and pm (with mirror planes) have been performed.…”

Section: Long Range Dynamic Dipole-dipole Couplingmentioning

confidence: 99%

“…Polarization Fourier transform infrared surface spectroscopy (PIRS), in combination with a diffraction technique, LEED or HAS (helium atom scattering) has been applied to observe the localized, as well as the collective, vibrations of simple molecules physisorbed on ionic single crystal surfaces: H 2 , CO, CO 2 , H 2 O, N 2 O, COS on NaCl(100) [36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53]; CO, CO 2 and N 2 O, H 2 O on MgO(001) [54][55][56][57][58][59], respectively, and others. PIRS has the advantage of being non-invasive, which is necessary for the study of adsorbed reactive, thermolabile and photosensitive HN 3 .…”

Section: Introductionmentioning

confidence: 99%

Adsorption of Hydrogen Azide on the NaCl(100) Single Crystal Surface. Orientational and Translational Ordering of the HN3 Monolayer as Revealed by PIRS, LEED and Spectra Simulation

Heidberg¹,

Hustedt²,

Oppermann³

et al. 2001

Zeitschrift Für Physikalische Chemie

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The adsorption of hydrogen azide HN 3 on NaCl(100) has been studied by means of polarization Fourier transform infrared spectroscopy PIRS and low energy electron diffraction LEED. The well-defined surface was prepared in-situ under UHV by cleaving a single crystal with as few dislocations as possible.Ordered molecular adsorption of HN 3 has been observed. Multiple absorptions of all four molecular vibrations with frequencies between 4000 and 1000 cm −1 , all nondegenerate in the gas, are found at 120 K. In particular, a quartet of strongly polarized sharp absorption lines for the asymmetric stretching vibration ν 2 at 2162.8, 2154.0, 2149.2, and 2138.3 cm −1 is obtained, the line at 2162.8 cm −1 being extremely weak in s-polarization. Saturation of adsorption, indicating the monolayer, is observed both upon dosing HN 3 in the low coverage range, where island growth is inferred, and desorbing HN 3 from multilayers. No domain orientation appears to be preferred. An activation energy of desorption of 43 ± 5 kJ/mol and a pre-exponential factor of 2.6 × 10 14±1.5 s −1 were determined.Isotopic mixture experiments with H 14 N 3 and H 14 N 15 N 14 N reveal that the four absorption lines of the ν 2 vibration are caused first by site splitting due to two energetically inequivalent HN 3 -species and second by Davydov splitting due to a strong correlation field between the dynamic dipoles. There are four molecules per adsorbate unit cell: two different pairs of energetically equivalent but translationally inequivalent molecules. Further, two different pairs of NH hydrogen bonds are observed. Tilt angles and intermolecular angles of the adsorbed molecules were determined. The translational symmetry of the adsorbate was derived by LEED. Simulation of the ν 2 quartet spectrum based on equations of classical electrodynamics was accomplished yielding the angles, lateral distances and dynamic vibrational couplings within the monolayer. Combining all results we propose a monolayer structure of angularly ordered zigzag chains of HN 3 molecules, where two molecules are linked by a hydrogen bond forming a dimer, while the other weaker hydrogen bond ties the dimers together or to a Cl − surface ion. Two HN 3 dimers make up the p(2 × 2) monolayer unit cell of 2D space group pg.

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'Internal' and 'external' vibrational modes of CO2/NaCl(001) studied by Fourier-transform infrared spectroscopy and helium atom scattering

Cited by 19 publications

References 31 publications

Monolayers of ortho-H2, para-H2, para-D2 and normal-H2 adsorbed on NaCl(001) single crystal surfaces

Monolayers of ortho-H2, para-H2, para-D2 and normal-H2 adsorbed on NaCl(001) single crystal surfaces

Helium Atom Scattering from Oxide Surfaces

Adsorption of Hydrogen Azide on the NaCl(100) Single Crystal Surface. Orientational and Translational Ordering of the HN3 Monolayer as Revealed by PIRS, LEED and Spectra Simulation

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