| Abstract: | Inelastic electron tunneling spectroscopy is used in the analysis of chemisorbed species of urea and alkylthiourea on the alumina surface using an Al-Al2O3-Pb tunnel junction. Tunneling spectra of urea, thiourea, N,N′-dimethylthiourea (DMTU), and tetramethylthiourea (TMTU) were taken and analyzed for designated band positions and intensities by comparing with the corresponding IR spectrum. These molecules seem to exhibit similar adsorption behavior onto alumina surface. Thiourea and urea interact with the surface through the nitrogen lone pairs and orient perpendicularly on the Lewis acid site of the alumina surface. DMTU and TMTU are still adsorbed through the nitrogen atoms, but the molecular plane has a somewhat inclined orientation to the alumina surface. |
