HREELS and XPS Studies of Ferrocene on Ag(100)

Abstract

High-resolution electron energy loss spectroscopy (HREELS) and X-ray photoelectron spectroscopy (XPS) have been used to investigate the adsorption of ferrocene on Ag(100) at 150 K. The HREELS data show that ferrocene adopts an orientation with the molecular axis perpendicular to the Ag(100) surface plane for low exposures. Additionally, no rehybridization is observed at the low temperature employed. Upon multilayer growth, however, the molecular axis becomes canted with respect to the surface normal. XPS for monolayer ferrocene gives Fe 2p binding energies of 707.9 and 720.8 eV for the 2p3/2 and 2p1/2 transitions, respectively, and C 1s binding energy of 284.9 eV. Monolayer surface coverage represents a molecular footprint of about one ferrocene per nine Ag surface atoms. Multilayer ferrocene grows in a layer-by-layer fashion and shows HREELS and XPS

Molecular and electronic structure of electroactive self-assembled monolayers

“…The C 6 SAM shows no Fe 2p XPS signal as expected whereas the Fe 2p XPS spectra corresponding to the ferrocene containing SAMs (FcC 6 and FcC 6 + C 6 ) show a Fe 2p 3/2 and Fe 2p 1/2 doublet located at 707.8 eV and 720.7 eV. The position of the doublet is in excellent agreement with previously reported values for adsorbed ferrocene 29 and is consistent with the presence of Fc in its reduced state given that the XPS Fe 2p 3/2 signal of the ferricenium cation is expected at 710.6 eV. 30 The S 2p XP spectra of all SAMs show a broad signal with a high binding energy shoulder that can be fitted with two sets of doublets each corresponding to the S 2p 3/2 and the S 2p 1/2 components with a spin orbit coupling of 1.2 eV.…”

π-Interactions as a tool for an easy deposition of meso-tetraferrocenylporphyrin on surfaces

“…7b, the major contribution comes from the sharp feature at B708 eV, associated with Fe(II) centres in the ferrocenyl moieties of H 2 TFcP. 24,32 The broader feature centred at B711 eV is assigned to Fe(III) of ferrocenium ions in the porphyrin derivative, which is accompanied by its weaker shake-up satellite at around 715 eV. Partial oxidation of ferrocenyl moieties likely occurs upon exposure to ambient air during sample preparation and was reported several times, especially upon immobilisation reactions on surfaces.…”

“…Partial oxidation of ferrocenyl moieties likely occurs upon exposure to ambient air during sample preparation and was reported several times, especially upon immobilisation reactions on surfaces. 32,33 Upon increase of the y angle, a more superficial portion of the surface can be investigated. In Fig.…”

Cobaltocene adsorption and dissociation on Cu(111)

“…When comparing initial cobaltocene adsorption on graphite [32] and Cu(1 1 1) (the work presented here) with other metallocenes, it seems fairly clear that cobaltocene is far less stable as a molecule on surfaces than ferrocene (Z − 1) [13][14][15][16][17][18][19][20][21][22] or nickelocene (Z + 1) [20], [23][24][25][26][27]. The big difference among these three metallocenes appears to be that the "nineteen electron" cobaltocene has a single unpaired electron resulting in a low ionization potential [32] of 5.56 eV [37] when compared to ferrocene (6.88 eV [37]) and nickelocene (6.51 eV [37]).…”

“…Of the many studies of molecular ferrocene [13][14][15][16][17][18][19][20][21][22], nickelocene [20][21][22][23][24][25][26][27][28][29][30][31] and cobaltocene [32] adsorption, the initial adsorption is associated (molecular) on most surfaces, when the adsorption is undertaken at substrate temperatures in the region of 100-200 K. Molecular metallocene adsorption has been observed on Ag(1 0 0) [13][14][15], [21], [22], [26], and [27], Cu(1 0 0) [15], [19], [21][22][23][24][25], Mo(1 1 2) [17] and [22], graphite [16], [18], and [32] and Si(1 1 1)-2 × 1 [20]. Nonetheless, initial nickelocene adsorption on Ni(1 0 0) [25] and NiO(1 0 0) [25] is dissociative even for substrate temperatures of 135 K. We might expect that cobaltocene adsorption, like that observed for other metallocenes, would also be molecular on substrates well below r...…”