Chemical reaction processes trigger

The total light (or electric) field at the surface contains contributions from both the incident and the reflected fields. These near-surface fields are the ones interacting with any adsorbate, triggering possible chemical reaction processes. The field components, in... 

Chemical anq>lificatioii, the process by which a cascade of chemical reactions are triggered by absorption of a photon, represents a landmark concept in relied photochemistry. Ch cal amplification leads to the efiScient use of the available light and, therefore, enables imaging systems with high sensitivity. Photopolymerization and photoresists are two commercially in rtant applications of this concept In conventional vinyl photopolymerization,... 

Figure 26. An electric (ionic) pulse arrives from the brain through a nerve to the muscle, where it triggers conformational changes in proteins and chemical reactions. All the processes are three-dimensional. The generator (brain) is at the same time an ionic conductor. (Reprinted from T. F. Otero in Polymer Sensors and Actuators, Y. Osada and D. De Rossi, eds., Fig. 1, p., 19. Copyright 19XX. Reprinted with permission of Springer-Verlag.)...

As shown in Section 2.2.7, chemical reactions may be triggered by electrons or holes from an electrode as illustrated by SrnI substitutions (Section 2.5.6). Instead of involving the electrode directly, the reaction may be induced indirectly by means of redox catalysis, as illustrated in Scheme 2.15 for an SrnI reaction. An example is given in Figure 2.30, in which cyclic voltammetry allows one to follow the succession of events involved in this redox catalysis of an electrocatalytic process. In the absence of substrate (RX) and of nucleophile (Nu-), the redox catalysis, P, gives rise to a reversible response. A typical catalytic transformation of this wave is observed upon addition of RX, as discussed in Sections 2.2.6 and 2.3.1. The direct reduction wave of RX appears at more negative potentials, followed by the reversible wave of RH, which is the reduction product of RX (see Scheme 2.21). Upon addition of the nucleophile, the radical R is transformed into the anion radical of the substituted product, RNu -. RNu -... 

At this point, the final specifications for the one or two chosen product(s) after selection process should be identified. This can be done using a three-step procedure. First, we define the product micro and macrostructure. Second, we rank the product s most important attributes, an effort that forces a review of how the product will be used. Third, we review any chemical triggers, that is, chemical stimuli which cause major changes in product properties. Finally, we turn to the manufacture itself, which relies on technical know-how of thermodynamics, chemical reaction kinetics, transport phenomena, and unit operations. Some of these ideas are illustrated in the following example. Except for a schematic of the manufacturing process, the many details related to the manufacturing plant are omitted in this discussion. 

The use of T2D-IR spectroscopy in its various modes is not limited to MLCT. It is applicable to all kinds of photo-triggered processes. Besides the investigation of electronically excited states, photo-chemical reactions like isomerizations and dissociations can be explored. Application to a photo-switchable peptide has already been demonstrated [10]. Conformational dynamics of biomolecules that are triggered by laser-induced T-jump or the control of pH by photo-acids, can also be investigated. 

When this molecule absorbs light, it rapidly isomerizes (changes its structure) to the all-trans form. This specific chemical reaction is the central event in human vision. The molecule is bound within a protein (the combination is called rhodopsin), the isomerization triggers a series of later processes, ultimately leading to an electrical signal which is sent to the brain. 

The DCC process involves an EDL-stabilized ceramic slurry that is destabilized by a time-delayed reaction involving enzyme catalysts. - The enzymes trigger chemical reactions that can be used to either increase the ionic salt content at a constant pH or shift the pH to the lER An increase in the salt concentration will... 

Emeline A. V., Polikhova S., Andreev N., Ryabchnk V. K. and Serpone N. (2002b), Photoinduced processes in heterogeneons gas-solid systems. Temperature dependence (100-600 K) and modelling of a snrface chemical reaction on zirconia that triggers photophysical events in the solid , J. Phys. Chem. B 106, 5956-5966. 

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