The adsorption of L‐cysteine on Au(110) in ultra‐high vacuum and electrochemical environments

Abstract

We have investigated the adsorption of L-cysteine (L-Cys) onto Au(110) in an electrochemical cell and under ultra-high vacuum (UHV) conditions using reflection anisotropy spectroscopy (RAS). The L-Cys saturated surfaces created by both deposition methods exhibit similar RA profiles which indicates a similar adsorption process. Our results are consistent with L-Cys binding to the Au(110) surface through a goldthiolate (Au-S) linkage. Heating the L-Cys saturated surface in UHV to 580 K results in the decomposition of the adsorbate and leaves behind a sulphur/Au surface composed of different structural domains.

The adsorption and stability of sulfur containing amino acids on Cu{531}

“…4B show the sulfur completely degenerating into its atomic form by 400 K. The evolution of the integrated atomic and molecular sulfur peak areas are shown in Fig. 4C and reveal that the transition process begins as low as 360 K, a much lower temperature than the 580 K 'break down' temperature discussed above for cysteine adsorbed onto a noble substrate [26,29,31,33]. A comparison of the C1s spectra for alanine on Cu{5 3 1} and Cu{1 1 0} [12,18] with the C1s spectra at 400 K in Fig.…”

“…Cysteine binds to these surfaces typically through a thiolate species (sulfur atom) ''singular" footprint, however the possibility of bonding through the amine group has also been discussed [13][14][15][26][27][28][29][30][31][32][33][34]. For the single bonded species commonly cited, the molecule has been observed in two conformations, a neutral and zwitterionic form within a self assembled monolayer array [13][14][15]26,[29][30][31][32][33][34]. The general consensus is that electrons are donated from the sulfur atom to the gold substrate to form a very strong bond that is stable up to approximately 580 K, where after the molecule breaks up leaving sulfur on the surface [26,29,31,32].…”

Optical signatures of thiolate/Cu(110) and S/Cu(110) surface structures

“…This result is consistent with the results of recent first-principles calculations. 41 Characterizing bonding interactions in UHV provides a basis for the interpretation of RAS results at the solid/liquid interface 42 and we anticipate that the thiolate-Cu͑110͒ RAS results presented here will provide a similar foundation for further work involving the assembly of thiol-derivatized molecules at metal/ liquid interfaces.…”

Probing chiral monolayers of cysteine on Au(110) using reflection anisotropy spectroscopy and second-harmonic generation

“…RAS measures the difference in reflectance, at near normal incidence, of light linearly polarized in two orthogonal directions at the surface plane of a cubic material : where r x and r y are the complex Fresnel reflection coefficients for the surface for light polarized in the x and y directions. Spectra were compared with previous RAS studies of the R ‐(+)‐enantiomer on Au(110) .…”