Université Paris-Sud, Institut des Sciences Moléculaires d'Orsay (ISMO), UMR 8214, Orsay, France.
Phys Chem Chem Phys. 2013 May 21;15(19):7220-7. doi: 10.1039/c3cp43750g.
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. CO2 and H2O were also directly identified at low temperature by vibrational analysis of the irradiated SAMs. At higher irradiation energy, both terminal functions and spacer alkyl chains are damaged upon electron irradiation, by resonant and non-resonant processes.
在室温及低温（~40 K）条件下，在超高真空（UHV）环境中研究了低能电子诱导的酸末端烷硫醇模型自组装单层（SAM）的降解。通过结合两种互补技术，原位探测了沉积在金上的 11-巯基十一烷酸（MUA，HS-（CH2）10-COOH）SAM 中低能电子诱导的化学修饰，这两种技术分别是高分辨率电子能量损失谱（HREELS），一种表面敏感的振动光谱技术，以及中性碎片的电子刺激脱附（ESD）分析。通过共振电子捕获机制，观察到 SAM 的末端官能团在 1 eV 左右时被选择性地破坏，观察到它们通过 CO、CO2 和 H2O 的形成和脱附而衰减。通过对辐照 SAM 的振动分析，在低温下还直接鉴定了 CO2 和 H2O。在更高的辐照能下，终端官能团和间隔烷基链在电子辐照下都会受到损伤，这是通过共振和非共振过程发生的。
