High-resolution infrared reflection absorption spectroscopy with a continuously tunable infrared laser: CO on Ru(001)

Abstract

A continuously tunable high resolution (0.2 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$) infrared laser has been applied for the first time to infrared reflection absorption spectroscopy (IRAS) of submonolayer coverages of adsorbed molecules on a well-defined metal surface, i.e., single crystal Ru(001). The sensitivity, resolution, and continuous tunability of the laser are demonstrated with vibrational spectra of submonolayer CO adsorbed on Ru(001) (CTHETA=0.65). The results indicate a smaller bandwidth of the CO stretch (5 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$) than previously observed. With an increase in substrate temperature from 85 to 300 K, a small frequency red shift of 2.5 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ is observed.