Understanding and Controlling Complex Chemical Processes

Clearly, advances in chemical imaging capabilities will result in more fundamental understanding of chemical processes. In this chapter, chemical imaging is addressed in the context of an overarching goal to understand and control complex chemical processes. 

In this report, chemical imaging is defined as the spatial and temporal characterization of the molecular composition, structure, and dynamics of any given sample—with the ultimate goal being able to both understand and control complex chemical processes. As illustrated by the case studies in Chapter 2, this ability to image or visualize chemical events in space and time is essential to the future development of many fields of science. 

Rate constant, the statistical dynamical quantity of most interest, is indispensable to our understanding and controlling of chemical reactions at the molecular level. In particular, derivation of the rate constant for an elementary chemical reaction is of essential significance since a complex reactive process may finally have a relationship to an individual elementary reaction step. There are various theoretical methods for computing rate constants for an elementary chemical reaction, and the development of the time-dependent quantum wave packet (TDQWP) method during the past two decades has enabled this... 

Ceramic boards are currently widely used in high-performance electronic modules as interconnection substrates. They are processed from conventional ceramic precursors and refractory metal precursors and are subsequently fired to the final shape. This is largely an art a much better fundamental understanding of the materials and chemical processes will be required if low-cost, high-yield production is to be realized (see Chapter 5). A good example of ceramic interconnection boards are the multilayer ceramic (MLC) stractures used in large IBM computers (Figure 4.11). These boards measure up to 100 cm in area and contain up to 33 layers. They can interconnect as many as 133 chips. Their fabrication involves hundreds of complex chemical processes that must be precisely controlled. 

Many materials are complex mixtures of multiple molecular species and components and each component can be in multiple chemical or physical states. Realtime determination of the components and their properties is important for the understanding and control of the manufacturing processes. This paper reviews a recently developed technique of 2D NMR of diffusion and relaxation and its application to identify components of materials. This technique may have further applications for the study of biological systems and in industrial process control and quality assurance. 

Successful reproduction (and sex) involves many complex chemical processes that can be disrupted at various points to reduce fertility and conception. Part of this process is under control of the endocrine system, and chemicals that affect the endocrine system are termed endocrine disruptors. In the 1950s, understanding of the endocrine system led to the development of birth control pills as a way to reduce fertility in humans. This is a desirable and planned use of endocrine disruptors. Subsequently, it was discovered that a number of chemicals released into the environment could disrupt the endocrine system and reduce fertility of wildlife. Some are concerned that exposure to these chemicals, such as DDT and dioxin (TCDD), may also affect human fertility (Table 17.1). Approximately 15% of couples of reproductive age are infertile. Endocrine disruptors may also affect fetal development, causing demasculization and feminization of the offspring, which in turn cause reduced fertility in the next generation. 

The development of theories and models for electron transfer (ET) in molecular and materials systems is an important and successful area of fundamental research. It is of great interest to both understand and control ET in a wide range of complex molecular and materials systems because of its importance in many physical, chemical and biological processes. ... 

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