Orientation of Physisorbed Fluoropropenes on Cu(111)

Abstract

Fourier transform infrared reflection absorption spectra (FT-IRAS) have been obtained for adsorbed monolayers of propene and a set of fluorinated propenes (CFH2CHCH2, CF3CHCH2, and CF3CFCF2) on the Cu(111) surface. These species interact weakly with the copper surface. The FT-IRAS spectra indicate that the molecules lie flat with the plane of the molecule defined by the CCC atoms essentially parallel to the surface regardless of the degree of fluorination. Quantitative analysis of the orientation of hexafluoropropene determines the tilt of the molecular plane with respect to the surface to be 11°. The results for propene indicate a molecular tilt of 20°. Where the ν(CC) mode can be identified in the spectra of the adsorbed molecules, there is no perturbation of its frequency, which indicates that there is little backdonation between the metal and the π* orbital of the propene.

FT-IRAS of Adsorbed Alkoxides: Fluorinated Ethoxides on Cu(111)

“…Thus, in principle, it is possible to determine the angles θ CC , between the C-C bond and the surface normal, and , between the plane of the molecular defined by the C-C-O atoms and the plane of the surface normal, for the average orientation of ethoxide on the Cu(111) surface. The results of the previous quantitative analysis 9 show that θ CC ) 70 ( 2°and ) 17 ( 2°, and the structure is shown in Figure 7A. CF 3 CH 2 O (ad) .…”

“…9 A base pressure of <1.0 × 10 -10 Torr was achieved by a cryopump and titanium sublimation pump. The chamber has two leak valves for exposing the metal crystal surface to sample gases.…”

“…The results are compared with the orientation determined for ethoxide on the Cu(111) surface. 9 The comparison reveals the influence of fluorination on the structure of adsorbed ethoxide.…”

Switching the Chirality of Single Adsorbate Complexes

“…[19] The conversion of 2* into 1 requires a bias voltage of about 200 mV (Figure 2 c) and correlates with the C = C stretching vibration at 204 meV (see Table T1 in the Supporting Information). [20] Interestingly, the back rotation requires a much higher bias voltage, which is related to the CH 3 stretching vibration. Therefore, the coupling of the C=C vibration to the rotation mode depends on the starting configuration.…”

Umwandlung der absoluten Konfiguration einzelner Adsorbatkomplexe

“…(Hintergrundinformationen, Tabelle T1). [20] Interessanterweise benötigt die Rück-rotation eine erheblich höhere Spannung, die mit der CH 3 -Streckschwingung korreliert. Also hängt die Kopplung der C=C-Schwingung an die Rotation stark von der Anfangskonfiguration ab, d. h., eine angeregte C=C-Schwingung in 1 kann nicht an diese Aktionsmode koppeln.…”