Absorption steps involved

For absorption, stripping, and distillation, there are three main steps involved in design ... 

Photopolymerization, in general, can be defined as the process whereby light is used to induce the conversion of monomer molecules to a polymer chain. One can distinguish between true photopolymerization and photoinitiation of polymerization processes. In the former, each chain propagation step involves a photochemical process [1,2] (i.e., photochemical chain lengthening process in which the absorption of light is indispensable for... 

The first step in a photoelectrochemical reaction is photon absorption (capture) by the substrate and the change in electron energy (photoexcitation) occurring in the substrate as a result of photon absorption. This step is followed by other chemical or electrochemical reaction steps involving the activated substrate. 

In the mechanism of a photochemical reaction, at least one step involves photons. The most important such step is a reaction in which the absorption of light (ultraviolet or visible) provides a reactive intermediate by activating a molecule or atom. The mechanism is usually divided into primary photochemical steps and secondary processes that are initiated by the primary steps. 

The nature of thiocyanato complexes of silver in non-aqueous solvents has recently been reassessed.145 IR and Raman spectra were used to show that when Ag+ was complexed by SCN, the species present and the equilibrium steps involved were solvent specific. Characteristic absorption bands are summarized in Table 24. In pyridine, complexation passed through [Ag2(SCN)]+ and AgSCN to [Ag(SCN)2], such that even when the [SCN ]T/[Ag+]T ratio was 0.059, 50% was present as the linear [Ag(SCN)2]- ion. 

As in the atomic system the first step involves a transition to a discrete upper state by light absorption. The wavelength of exciting light is chosen to coincide with an absorption band of a specific isotope species. Absorption bands of other isotope species must be sufficiently separated from the exciting line so that only a desired isotopic species is excited. 

The pathway from N-demethylation to exhaled C02 involves a number of steps many of which are also metabolic, but catalyzed by several enzyme systems distinct from the initiating CYP isoform. A critical assumption is that all steps prior to (e.g., absorption for a probe that is not administered parenterally) or subsequent to N-demethylation are not rate limiting. In general, the steps involved in intermediary metabolism of the one-carbon pool meet this criterion. However, a percentage, estimated to be between 37% and 57%, of labeled... 

As shown in Figure 6.49a, the cracks grow by slip dissolution due to diffusion of active water molecules, halide ions, etc., to the crack tip, followed by a rupture of the protective oxide film by strain concentration, fretting contact between the crack faces. This is followed by dissolution of the fresh exposed surface and growth of the oxide on the bare surface. For the alternative mechanism of hydrogen embrittlement in aqueous media, the critical steps involve diffusion of water molecules or hydrogen ions to the crack tip reduction to hydrogen atoms at the crack tip surface diffusion of adsorbed atoms to preferential surface locations absorption and diffusion to critical locations in the... 

In organic cells, however, the steps involved in the generation of photo-current are (1) light absorption, (2) exciton creation, (3) exciton diffusion, (4) exciton dissociation in the bulk or at the surface, (5) field-assisted carrier separation, (6) carrier transport, and (7) carrier delivery to external circuit. Assuming that only the excitons which reach the junction interface produce free carriers, if the blocking contact is illuminated [65],... 

Photon absorption in the PS II/OEC leads to charge separation in the PS II reaction center to generate the oxidized reaction center, P-680 (Ref. 18 Chapter 4, this volume.) The simplest scheme for subsequent electron transfer steps involves only the intermediate carrier, Z, and the Mn ensemble at the water-splitting site ... 

The sequence of steps involved in fluorescence is described in Fig. 2. The initial absorption takes the molecule or ion pair from the ground electronic singlet state (So) to the electronically excited singlet state (5i), and the resulting absorption (excitation) spectrum should resemble that showm in Fig. 3a. 

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