University of Bremen, Institute for Applied and Physical Chemistry, Fachbereich 2 (Chemie/Biologie), Leobener Straße/NW 2, Postfach 330440, 28334 Bremen, Germany.
Chem Soc Rev. 2013 Dec 21;42(24):9219-31. doi: 10.1039/c3cs60180c. Epub 2013 Oct 2.
Controlling the outcome of reactions is a central issue of chemical research. Physical tools can achieve this if they are able to precisely dissociate specific bonds of a molecule. However, to control synthesis, such tools must induce the formation of new bonds between two reactants to yield a more complex product. In the ideal case of an atom efficient synthesis, this product would contain all or at least most of the initial material. An electron beam is a physical tool that is capable of preparing molecules in reactive states or, at low electron energies, of initiating highly selective bond dissociation. The resulting fragments in turn can react with other molecules to yield stable products. This tutorial review focuses in particular on such low-energy electron-initiated molecular syntheses and their applications in the modification of surfaces. It thus emphasizes strategies towards the controlled and predictable formation of more complex products from small reactants initiated by interaction with low-energy electrons either through selective bond dissociation or formation of specific reactive molecular species. However, selective bond dissociation is not always desirable. This is briefly illustrated by the case of electron beam induced deposition where additional strategies may be required to control product formation.
控制反应的结果是化学研究的核心问题。如果物理工具能够精确地使分子的特定键断裂，它们就可以实现这一点。然而，要控制合成，这些工具必须在两个反应物之间诱导形成新的键，以产生更复杂的产物。在原子效率合成的理想情况下，该产物应包含全部或至少大部分初始材料。电子束是一种物理工具，它能够将分子制备成反应状态，或者在低电子能量下，引发高度选择性的键断裂。由此产生的碎片继而可以与其他分子反应，生成稳定的产物。本综述特别关注这种低能电子引发的分子合成及其在表面修饰中的应用。因此，它强调了通过与低能电子相互作用，从通过选择性键断裂或形成特定反应性分子物种来起始的小分子反应物中，有控制地和可预测地形成更复杂产物的策略。然而，选择性键断裂并不总是可取的。电子束诱导沉积的情况就是一个简短的例证，在这种情况下，可能需要额外的策略来控制产物形成。
