HREELS STUDIES OF FORMAMIDE ON PT(111) - HYDROGEN-BONDING INTERACTIONS BETWEEN ADSORBATES

The adsorption properties of formamide, HCONH2, on Pt(111) have been studied using high-resolution electron energy loss spectroscopy (HREELS). At low dosages, dissociative adsorption of formamide at 170 K results in the formation of coadsorbed NH3 and CO. The onset of molecular adsorption occurs just prior to formation of a monolayer. At saturation monolayer coverages, hydrogen-bonding interactions between the chemisorbed molecules result in red-shifting of the ν(NH2) vibrational frequency from the gas phase value of 3570 to 3307 cm-1. The linewidths of the νs(NH2) and νa(NH2) modes are broadened into a singular peak due to enhanced coupling with NH2 modes of lower frequency. In the case of HCOND2, the νs(ND2) and νa(ND2) peaks are distinctly resolved. Upon heating multilayer coverages of formamide, the hydrogen-bonding interactions lead to autocatalytic desorption of formamide at 223 K. © 1990.