HIGH-RESOLUTION XPS OF BITHIOPHENE ON CLEAN AND S MODIFIED NI(110)

In this contribution we demonstrate the usefulness of HR-XPS with sync hrotron radiation by applying it to reveal the nature of various bondi ng configurations of bithiophene monolayers on clean Ni(110) and the s ulphur c(2 X 2)S (Theta(S) = 0.5) and p(4 x 1)S (Theta(S), = 0.75) ove rlayer structures. The resolution was only limited by natural line wid ths and allowed two sulphur sites in the p(4 X 1)S reconstruction to b e distinguished from the c(2 X 2)S sulphur site in agreement with prop osed models for the reconstructions. For the molecule the linking carb ons could be identified. Only small differences in C-K and S L(2,3) XP S energies were observed despite strong differences in bonding being s uggested by the thermal evolution of the monolayers. It is argued that the differences in the observed S/C XPS intensity ratios are due to d ifferences in adsorbate geometry for the three substrates.