Zhou Chuanzhen, Walker Amy V
Department of Chemistry and Center for Materials Innovation, Washington University in St. Louis, Campus Box 1134, One Brookings Drive, St. Louis, MO 63130, USA.
Langmuir. 2006 Dec 19;22(26):11420-5. doi: 10.1021/la0618519.
We have investigated the mechanism of UV photopatterning of binary alkanethiolate self-assembled monolayers (SAMs) adsorbed on Au(111) using time-of-flight secondary ion mass spectrometry. The SAMs were photopatterned using a 500 W Hg arc lamp. The patterning process is strongly dependent on the wavelength of light used. When an unfiltered arc lamp is employed, IR light impinges on the sample and causes considerable sample heating. Methyl-terminated SAMs with less than 14 carbons in the chain melt at the temperatures reached and become very disordered and so can be easily displaced by a second SAM. This leads to significant pattern degradation ("erosion"). SAMs with greater than 14 carbons undergo a transition to an incommensurate phase but remain stable on the surface, and the pattern is retained. When the IR light is filtered out, a different behavior is observed. UV-photopatterned methyl-terminated SAMs with 10 carbons in the chain are stable. Terminal group interactions, such as H-bonding, provide extra stabilization energy during photopatterning, so some patterns with shorter carbon chains may also be stable. The displacement of the photooxidized SAMs on the patterned surface follows kinetics similar to that of large-area SAM formation.
我们使用飞行时间二次离子质谱法研究了吸附在Au(111)上的二元硫醇盐自组装单分子层（SAMs）的紫外光图案化机制。SAMs通过500 W汞弧灯进行光图案化。图案化过程强烈依赖于所使用光的波长。当使用未过滤的弧光灯时，红外光照射到样品上并导致样品显著升温。链中碳原子少于14个的甲基封端的SAMs在达到的温度下会熔化，变得非常无序，因此很容易被第二种SAM取代。这会导致显著的图案退化（“侵蚀”）。碳原子数大于14个的SAMs会转变为非公度相，但在表面上保持稳定，图案得以保留。当滤除红外光时，会观察到不同的行为。链中含有10个碳原子的紫外光图案化的甲基封端的SAMs是稳定的。端基相互作用，如氢键作用，在光图案化过程中提供额外的稳定能量，因此一些碳链较短的图案也可能是稳定的。图案化表面上光氧化的SAMs的取代遵循与大面积SAM形成相似的动力学。
