Knowledge Bank

The infrared spectrum of CO adsorbed on NACL(100) has been obtained with a Fourier Transform Infrared Spectrometer (1). The apparent band width of the adsorbed CO decreased from $1cm-1$ at 60K to $0.5cm-1$ at 40K. The instrument resolution is $0.5cm-1$ and the CO bandwidth at 40K is limited by the spectrometer resolution. The observed band shape is a convolution of the Instrument Line Shape (ILS) and the true band shape. The true band shape was obtained by deconvoluting the ILS from the observed band shape (2). The temperature dependent change in both the band width and frequency shift is compared with predictions from existing theoretical models for band broadening mechaniams of adsorbed molecules on surfaces.