Incoherent Inelastic Neutron Scattering: Vibrational Spectroscopy of Adsorbed Molecules on Surfaces

Given the variety of laboratory-based, surface-sensitive vibrational spectroscopies, the need for an additional vibrational spectroscopy such as incoherent inelastic neutron scattering (IINS), which is based on a centralized user facility, may not be immediately obvious. In the absence of special capabilities or suitability for probing relevant classes of materials, it would be difficult to justify such experiments owing to both the expense and the limited accessibility of these facilities. However, the range of incident wavelengths (0.5–15.0 A) and corresponding energies (0.8–300 meV) accessible with neutrons clearly distinguishes IINS from more conventional probes of molecular vibrations. In fact, incoherent inelastic neutron scattering embodies a number of attributes that make this reactor-based technique an often unique method for surface characterization and a powerful complement to other techniques.