Thermal stability of succinate and acetate on a Cu(1Â 1Â 0) surface

We made a helium atom beam scattering (HAS) apparatus to study the thermal dynamics of adsorbed organic molecules on a surface. The apparatus had an angular resolution of 6° and energy resolutions of 20%, with an incident energy of Ei = 63 meV. We measured the thermal stability of acetic acid (CH3-COOH) and succinic acid (HOOC-CH2-CH2-COOH) structures on a Cu(1 1 0) using the DW-plot technique (the temperature variation of intensity of the He beam specularly reflected from the surface). We found that the desorption temperatures derived from DW-plots are 540 K for low-coverage acetate, 550 K for c(2 × 2) acetate and 590 K at succinate. The desorption temperature of succinate is higher than acetate, which is interpreted by a larger number of carboxylates in one molecule.