Structure of monolayers of short chain n-alkanoic acids (CH3(CH2)nCOOH, n = 0-9) spontaneously adsorbed from the gas phase at silver as probed by infrared reflection spectroscopy

Abstract

This paper presents the results of an infrared spectroscopic and wettability examination of monolayers formed by the spontaneous adsorption of short chain n-alkanoic acids ( C H~( C H Z )~C O O H , n = 0-9) from the gas phase onto Ag. The infrared spectral data, collected in an external reflection mode, indicate that the monolayers chemisorb as the corresponding salt and that the chains contain all-trans conformational sequences for n = 1-9. The chemisorption process is further exemplified by the formation of a carboxylate group that is symmetrically bound at Ag as either a bidentate or bridging ligand. The conformational insights are developed on the basis of an unusually prominent series of the methylene wagging progression. An in-depth analysis resulted in the complete assignment of the fundamental modes in the progression as well as a reassignment of the C C stretch in the region of this progression. Structural insights developed from the infrared spectral data and contact angle measurements are compared to analogous monolayers formed from dilute solution. This comparison points to the subtle, but important, role of solvent in influencing the structure of the monolayer.

Synthesis of Gold Nanoparticles in a Winsor II Type Microemulsion and Their Characterization

“…3b, a new band appearing at 1415 cm −1 can be assigned to a scissoring vibration mode of the methylene group adjacent to the Au-S bond. Our result is consistent with those reported by others (9,21). Thus, the appearance of this band also confirms the formation of a Au-S bond.…”

“…3. The main bands in these spectra are clearly seen (9,(15)(16)(17)(18)(19)(20)(21). The similarity of the features of FT-IR spectra confirms (a) that the thiol is an essential component of the composite nanoparticles and (b) that the thiol molecule is not leached out during several washings of the solid.…”

Surface-Enhanced Raman Scattering from Oleate-Stabilized Silver Colloids at a Liquid/Liquid Interface

“…This is consistent with the enhanced acidity of carboxylic acids at an Ag surface. 27 Oleate anions would exist as silver salts on the silver colloids, because it is known that an appreciable number of positively charged Ag atoms exist on the Ag colloids. 28 This has been supported from the reported IR spectra, 29 in which the νas(COO -) of silver carboxylate is 45 cm -1 lower than that of sodium oleate observed in our SERS spectra.…”

Construction of Various Self-assembled Films and Their Application as Lubricant Coatings

“…The spatial orientation of the tail groups also has a prominent impact on adhesion and friction. For example, an "odd-even" effect is observed for SAMs with same tail groups but different CH 2 number (odd or even) in the alkyl chain (Chang et al, 1994;Lee et al, 2001;Smith & Porter, 1993;Tao, 1993;Wong et al, 1998). As shown in Fig.…”