Inelastic electron tunnelling spectroscopy (IETS) of carboxylic acids and related systems chemisorbed on plasma-grown aluminium oxide. Part 1.—Formic acid (HCOOH and DCOOD), acetic acid (CH₃COOH, CH₃COOD and CD₃COOD), trifluoroacetic acid, acetic anhydride, acetaldehyde and acetylchloride

Abstract

A study of the inelastic electron tumelhg spectra GETS) of formic acid, [2H2]formic acid, acetic acid, [2H4]acetic acid and trifiuoroacetic acid shows that these chemisorb from the vapour phase on to plasma-grown aluminium oxide as surface-bound formates and acetates. Detailed vibrational mode band assignments are made and the carboxylates are deduced to be adsorbed symmetrically on, though not necessarily perpendicular to, the oxide surface. The plasma-grown oxide shows enhanced reactivity to acetaldehyde over bulk y-alumina behaviour. Evidence is obtained for the involvement of two surface-site types in reaction with trifluoroacetic acid.

Low‐power r.f. plasma oxidation of aluminium

“…Hence, the different rates of oxidation may suggest that the water plasma is able to establish more readily the equilibrium concentration of water required for rapid oxide growth. The formation of a thermodynamically stable film requiring a certain hydroxyl ion concentration is supported by Brown et al,3 who indicated that stable oxide films could be produced only with trace quantities of water present in the plasma gas.…”

“…6 The plasma film was reported to be similar to alumina, 7 which contained hydroxide when the aluminium substrate was maintained at temperatures below 150°C. 1,3,8 Evidence suggested that the oxide crystallinity increased with temperature. Mechanistic studies indicated that oxygen anions may have played a role in the oxidation process.…”

“…1 The attributes of plasma-prepared films have been utilized for fundamental surface studies of aluminium oxide. 2,3 The ability to clean efficiently the metal surfaces also makes plasma oxidation a suitable surface treatment for adhesive application. 4,5 Studies of d.c. plasma oxidation of aluminium indicated that the film growth rate was dependent on the positive sample bias, substrate temperature and water concentration of the oxygen gas used.…”

Mechanism of Lac repressor switch‐off: orientation of the Lac repressor DNA‐binding domain is reversed upon inducer binding

“…2B) and eluted from the gel. DNA fragments labeled at 5'-terminus and bound to peptides (D l-D5) were subjected to A + G reaction of sequencing protocol [17]. The idea is that the sequencing ladder must tively.…”

Site specificity and chromatographic properties of E. COLI K12 and EcoRII DNA‐cytosine methylases

“…DNA was degraded to pyrimidine sequences [13]. The released pyrimidine fragments were separated according to chain length (isopliths) and base composition by thin-layer chromatography on DEAEcellulose (Reanal, Hungary) [14].…”