Low-energy electron induced resonant loss of aromaticity: consequences on cross-linking in terphenylthiol SAMs.

Aromatic self-assembled monolayers (SAMs) can be used as negative tone electron resists in functional surface lithographic fabrication. A dense and resistant molecular network is obtained under electron irradiation through the formation of a cross-linked network. The elementary processes and possible mechanisms involved were investigated through the response of a model aromatic SAM, p-terphenylthiol SAM, to low-energy electron (0-10 eV) irradiation.

Selective terminal function modification of SAMs driven by low-energy electrons (0-15 eV).

Low-energy electron induced degradation of a model self-assembled monolayer (SAM) of acid terminated alkanethiol was studied under ultra-high vacuum (UHV) conditions at room and low (~40 K) temperatures. Low-energy electron induced chemical modifications of 11-mercaptoundecanoic acid (MUA, HS-(CH2)10-COOH) SAMs deposited on gold were probed in situ as a function of the irradiation energy (<11 eV) by combining two complementary techniques: High Resolution Electron Energy Loss Spectroscopy (HREELS), a surface sensitive vibrational spectroscopy technique, and Electron Stimulated Desorption (ESD) analysis of neutral fragments. The SAM's terminal functions were observed to be selectively damaged at around 1 eV by a resonant electron attachment mechanism, observed to decay by CO, CO2 and H2O formation and desorption.

Low-energy electron scattering on deuterated nanocrystalline diamond films-a model system for understanding the interplay between density-of-states, excitation mechanisms and surface versus lattice contributions.

Electron energy loss spectrum, elastic reflectivity and selected vibrational excitation functions were measured by High Resolution Electron Energy Loss Spectroscopy (HREELS) for deuterated nanocrystalline dc GD CVD diamond films. The electron elastic reflectivity is strongly enhanced at about 13 eV, as a consequence of the second absolute band gap of diamond preserved up to the surface for D-nano-crystallites. The pure bending modes δ(CD(x)) at 88 meV and 107 meV are dominantly excited through the impact mechanism and their vibration excitation functions mimic the electron elastic reflectivity curve.

Chemistry induced by low-energy electrons in condensed multilayers of ammonia and carbon dioxide.

We have investigated by means of HREEL spectroscopy electron induced reactivity in a binary CO2 : NH3 ice mixture. It was shown that the interaction of low energy electrons (9-20 eV) with such mixtures induces the synthesis of neutral carbamic acid NH2COOH and that flashing the sample at 140 K induces the formation of ammonium carbamate. The products have been assigned by FTIR spectroscopy of a CO2 : NH3 mixture heated from 10 K to 240 K.