In situphotoelectron spectroscopy study of water adsorption on model biomaterial surfaces

Abstract

Abstract. Using in situ photoelectron spectroscopy at near ambient conditions, we compare the interaction of water with four different model biomaterial surfaces: self-assembled thiol monolayers on Au(111) that are functionalized with methyl, hydroxyl, and carboxyl groups, and phosphatidylcholine (POPC) lipid films on Silicon. We show that the interaction of water with biomaterial surfaces is mediated by polar functional groups that interact strongly with water molecules through hydrogen bonding, resulting in adsorption of 0.2-0.3 ML water on the polar thiol films in 700 mTorr water pressure and resulting in characteristic N1s and P2p shifts for the POPC films. Provided that beam damage is carefully controlled, in situ electron spectroscopy can give valuable information about water adsorption which is not accessible under ultra-high vacuum conditions.

Reactivity of mesoporous carbon against water – An in-situ XPS study

“…The small intensity difference is equally distributed between the species II-V. However, the component VI at 534.2 eV, which can be assigned to carboxylic acid functional groups [25,26] or chemisorbed water [14,[16][17][18][19][20] according to the literature, is abundant in slightly higher proportion in sample MC_1 in comparison to the sample MC_2 after the butanol treatment.…”

“…It is generally agreed to the discrimination of minimum two different oxygen species, the double bonded oxygen at lower binding energies (~531 eV) and the single bonded oxygen at higher binding energies (~533 eV) [15]. Additionally, a third species at higher binding energies is commonly considered in the fit, assigned to adsorbed water or oxygen [17,20,26,27,33] chemisorbed H2O [14,[16][17][18][19][20] [28] VII 535 gas phase H2O [14] For the present work we also tried to involve considerations on structural elements that are predetermined by the synthesis procedure. Based on the polymeric precursor of the mesoporous carbon a broad variety of oxygen functional groups is possible for the carbon samples.…”

“…An additional feature for the measurements under water vapor was detected at 535 eV and corresponds to the water gas phase peak [14].…”

A versatile photoelectron spectrometer for pressures up to 30 mbar

“…9,15 Increasing availability is one of the key challenges if HPXPS is to be utilized to its full potential in a wide variety of subject areas, and indeed in the recent years there has been renewed interest in the development of laboratory-based HPXPS instruments utilizing differentially pumped analyzers and focused X-ray sources. 9,16,17 In processes ranging from heterogeneous catalysis 18 and electrochemical reactions in devices such as fuel cells, 19 solar cells, 20,21 and batteries [22][23][24] to environmental chemistry 25 and biomaterials 26 HPXPS is a fast-growing and valuable addition to the suite of advanced characterization techniques available to the scientific community. Below we report on a design allowing for home laboratory-based HPXPS measurements at pressures above the room temperature vapour-pressure of water and with a flexible configuration for efficient studies of a large variety of systems.…”

In situ gas–surface interactions: approaching realistic conditions

“…These interaction systems are important not only to biology and electrochemistry in general, but also for heterogeneous catalysis, where water is a well-known poison of catalytic reactions. Two such studies are presented here [18,19].…”