Photostationary state expression

Equation (12-17) is called the photostationary state expression for ozone. Upon examination, one sees that the concentration of ozone is dependent on the ratio NO2/NO for any value of k. The maximum value of k is dependent on the latitude, time of year, and time of day. In the United States, the range of k is from 0 to 0.55 min T Table 12-5 illustrates the importance of the NO2/NO ratio with respect to how much ozone is required for the photostationary state to exist. The conclusion to be drawn from this table is that most of the NO must be converted to NO2 before O3 will build up in the atmosphere. This is also seen in the diurnal ambient air patterns shown in Fig. 12-2 and the smog chamber simulations shown in Fig. 12-3. It is apparent that without hydrocarbons, the NO is not converted to NO2 efficiently enough to permit the buildup of O3 to levels observed in urban areas. 

The concentrations of electrons and holes in the conduction and valence bands, n and p, in the photostationary state under photon irradiation are expressed, respectively, in Eqn. 10-1 ... 

Equation 3.23 is derived without truncation above any order by assuming that the geometrical order parameters, A2, of the orientational distribution of the A and B isomers are equal at the photostationary state of irradiation. Although this assumption physically mirrors a uniform molecular orientational distribution, it does simplify considerably the expression of the photostationary-state orientational order and provides a simple law for steady-state photo-orientation characterization. Equation 3.23 holds when analysis is performed at the irradiation wavelength, and fits by Equations 3.22 and 3.23 allow for the measurement of 2 (cos [Pg.78]

This expression has been called the photostationary state relation. 

The difference between Eq. (34.100) and the usual equilibrium expression [A2] = i [A], should be noted. In the photostationary state in the condition for which Eq. (34.100) is appropriate, the concentration of dimer is independent of the concentration of monomer. 

Recently, we have investigated in detail the steady state and transients of the photoinduced polar order and its related anisotropy in both trans and cis molecular distributions [70]. The effect of all the physical parameters involved in the PEP phenomena has been considered. These include molecular anisometry, pump intensity, pump polarization, strength of the poling field, molecular mobility, and retention of memory of the molecular orientation. Here, we discuss the photostationary state of the PEP process by means of analytical expressions. 

The most convenient experimental measure of excimer fluorescence under photostationary-state conditions is the ratio Ij /I, where I and I are the emission intensities of the excimer ana monomer bands, respectively. The analysis of the kinetic scheme (equation A) leads to the following expression for the ratio ... 

Treatment of kinetic scheme 1, assuming photostationary excited state conditions, results in the following expression for the ratio of fluorescence quantum yields and of excimer and monomer respectively ... 

Thus, both transient and photostationary trapping experiments may be interpreted Quantitatively if an expression for the donor excitation function G (t) is available. In Section 2.2 we outline the development of an expression for G (t) for an aryl vinyl polymer in dilute solution. Here energy migration from a single monomer donor state to a single excimer trap state is analyzed by a one-dimensional model. We will present the analysis in more detail than the subsequent discussion of various many body theories because the treatment is straightforward and concise. This will allow the fundamental approach to be understood more clearly without the extensive mathematics required for the many-body treatment. 

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