Abstract

First, electrochemically controlled in situ atomic force microscopy (AFM|) and surface enhanced Raman spectroscopy (SERS) are utilized to obtain information in two types of additives used in Cu electrodeposition process. AFM study shows that a thick polymeric film formed between cuprous ion and an additive, benzoltriazole (BTA), is responsible for the smooth deposition feature obtained in BTA-containing deposition solutions. After the reduction of the film, the Cu surface roughness increases slightly due to the restricted diffusion of Cu species through the Cu-BTA film during Cu reduction. SERS is utilized to elucidate details of the interaction between Cu and another additive system, polyethylene glycol (PEG) and chloride ion, in Cu deposition solution. Systematic spectra analysis indicates that a complex containing PEG, Cu(I) and chloride ion is formed through a chloride bridging site on Cu electrode surface at more positive potentials. Calculations of the vibrational modes have also helped to generate molecular models of the complex structure.

Second, soft imaging mode of AFM and phase modulated ellipsometry are used to observe the phase transition process of supported lipid bilayer systems with and without the influence of other macromolecules. Addition of a weak polyelectrolyte, poly(methacrylic acid) (PMA), to a supported phospholipid bilayer depresses the melting temperature and alters the morphology of the bilayer in the gel phase. AFM study of the gel-fluid phase transition in supported phospholipid bilayers shows that at ∼5°C above T_m, AFM studies reveal the presence of a secondary phase transition. The secondary phase transition occurs as a consequence of decoupling between the two leaflets of the bilayer due to enhanced stabilization of the lower leaflet with either the support or the water entrained between the support and the bilayer. Addition of the transmembrane protein gramicidin A or construction of a highly defected gel phase results in elimination of this decoupling and removal of the secondary phase transition.