Weakly Chemisorbed Ammonia Species at a Cu(110) Surface

Abstract

Non-dissociative adsorption of ammonia on a Cu(110) surface leads to the formation of two distinct entities between 80 and 298K. A single XP N(1s) peak at 401 eV and the VEEL spectra characterize the a ammonia species which is primarily physically coordinated to surface sites via diverse types of hydrogen bonds. The β picture is clearly evident by the persistent R<inf>xy</inf> mode at 410 cm-1. Direct interaction between the 'monolayer' and most of the 'overlayer' NH<inf>3</inf> groups reduces the Bronsted acidity of surface copper atoms. No N-H bond rupture occurs prior to the transformation of the β pattern back into the form and an ammonia-free surface is regenerated eventually.