caa a22 4500 378907824 CHVBK 20180305123534.0 cr unu---uuuuu 161128e20040801xx s 000 0 eng 10.1524/zpch.218.8.973.35980 doi (NATIONALLICENCE)gruyter-10.1524/zpch.218.8.973.35980 Physisorption of Small Molecules on Single Crystal Alkali Halide Surfaces: CO and N2 Adsorbed on KCl(100) [Elektronische Daten] [J. Vogt, Helmut Weiss] The adsorption of CO and N2 on KCl(100) single crystal cleavage planes has been investigated by means of low energy electron diffraction (LEED) at primary currents in the nA range as well as polarization infrared spectroscopy (PIRS) in transmittance geometry. These isoelectronic adsorbates behave very similarly, and three different adsorption phases can be distinguished as a function of surface coverage for both of them. Initially a (1×1) structure is observed and assigned to a commensurate monolayer with one molecule per KCl ion pair. The CO infrared spectrum of this ‘phase I' is characterized by a doublet absorption of the CO stretching vibration, which is discussed in the context of a correlation field splitting. The lack of superstructure diffraction peaks is attributed to a high degree of orientational disorder in this phase. From LEED adsorption isotherms the isosteric heat of adsorption of N2 has been determined to be 11±3kJmol−1. Upon increase in coverage by 50% ‘phase II' is formed which exhibits a large number of additional diffraction spots. It is assigned to a bilayer in which the second layer is only half filled. Based on the LEED experiments a structure model is proposed in which the second layer is characterized by growth in rows along the [210] direction and a high degree of roughness in the perpendicular direction. This model can explain all experimentally observed main features. Finally upon further exposure formation of three-dimensional solid is observed, which proceeds via Stransky-Krastanov growth of crystalline 3D clusters with the structure of the low-temperature cubic α-phase. A simulation of the CO cluster infrared spectra within the dipole-dipole coupling approach can reproduce all major observed vibrational features. © 2004 Oldenbourg Wissenschaftsverlag GmbH Thermodynamics & statistical physics nationallicence Laboratory techniques, experiments nationallicence Physical chemistry nationallicence Vogt J. aut Weiss Helmut aut Zeitschrift für Physikalische Chemie/International journal of research in physical chemistry and chemical physics Oldenbourg Wissenschaftsverlag GmbH 218/8/2004(2004-08-01), 973-995 0942-9352 218:8/2004<973 2004 218 zpch https://doi.org/10.1524/zpch.218.8.973.35980 text/html Onlinezugriff via DOI 1 research article jats NATIONALLICENCE 856 40 https://doi.org/10.1524/zpch.218.8.973.35980 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Vogt J. aut NATIONALLICENCE 700 1- Weiss Helmut aut NATIONALLICENCE 773 0- Zeitschrift für Physikalische Chemie/International journal of research in physical chemistry and chemical physics Oldenbourg Wissenschaftsverlag GmbH 218/8/2004(2004-08-01), 973-995 0942-9352 218:8/2004<973 2004 218 zpch CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-gruyter