Incident photon flux density

Fig. 17 TPA and single-photon absorption rates versus incident photon flux density calculated using parameters from Table 1 for the case of excitation by pulsed SPDC soimce. Diameter of the irradiated area is 0.8 xm. The dashed lines emphasize the photon flux density and the entangled photon TPA rate provided by the model source...

C. If equal but low incident photon flux densities are simultaneously used at both 550 and 710 nm, what is the maximum quantum yield for CO2 fixation for each beam ... 

The absorbance is unaffected by changes in the incident photon flux density. 

A. The number of photons required per oxygen evolved is derived from the initial linear part of the curve describing the relationship between incident photon flux density and oxygen evolution ... 

This relation can be used, for example, to calculate volumetric productivity of a photobioreactor at different biomass concentrations when assuming a constant incident photon flux density Iph(O)- In Fig. 26 results are shown for a photobioreactor with an optical depth of 3 cm. The shape of this relation will be discussed later after having introduced a similar approach based on the model of Jassby and Platt. 

Applying all possible combinations of incident photon flux density, pond depth, and hydraulic retention time, Kroon et al. built a model to predict the algal biomass... 

This is actually the increase of the dark current due to illumination and is a dc value (valid for/= 0 Hz). Here rj denotes the quantum efficiency of the detector, < ) is the incident photon flux density, A is the detector active area. The factor T denotes the photoelectric gain or photogain (the ratio between the number of electrons flowing through the electric circuit and the number of absorbed photons). The fundamental equation of photoconductivity is also valid without changes for the short circuit current of a photovoltaic detector (photodiode operating in photo-conductive mode). In that mode of operation T = 1 in most of the cases. 

Fig. 4 shows the illustration of a double ionization chamber. We describe the process of measuring the photoabsorption cross sections as follows, /q denotes the incident photon flux coming into the chamber filled with atoms or molecules of the number density n, I and I denote the photon fluxes entering and leaving plate 1, respectively, and I2 and I2 denote the photon fluxes entering and leaving plate 2, respectively. The ion currents q and q collected by plates 1 and 2, respectively, are expressed as... 

Photon flux density and the average power of the incident beam were varied in a wide range that exceeded the current possibihties. Highest estimates of the photon-pair yields from SPDC sources, given in the hterature, are in the megahertz range [74]. Therefore we assiune an overestimated pair rate of 10 s which corresponds to the photon flux density of 4 x 10 cm s for a circiflar area with diameter of 0.8 pm. 

In Equation 17.9, Isc is the photocurrent density produced by the cell, l the excitation wavelength, and I the incident photon flux. 

The highest photon flux density normally encountered by plants occurs when the sun is directly overhead on a cloudless day, in which case the photosynthetic photon flux (PPF) for wavelengths from 400 to 700 nm is about 2000 pmol m-2 s-1 on a horizontal plane (Chapter 4, Section 4.1D). The average chlorophyll concentration in chloroplasts is approximately 30 mol m-3 (Chapter 4, Section 4.4D), and in passing through a chloroplast 2 pm thick about 30% of the incident PPF is absorbed. We can therefore estimate how often an individual chlorophyll molecule absorbs a photon ... 

Before photocurrent excitation spectra can be normalised to allow for the wavelength dependence of the illumination intensity, it is essential to establish the relation between the photocurrent response and the incident photon flux. This can be done using calibrated neutral density fdters. The relationship is generally not linear for photoconductive systems or for systems in which processes such as surface recombination or photocurrent multiplication occur (Peter, 1990). The incident photon flux can be measured using a UV-enhanced silicon photodiode with known sensitivity. 

In the numerical calculations presented in the figures of this section, we used the approximation of an equivalent gray medium (see Eqs. (35) and (36)). In this case, the gray radiative properties are used directly in the expressions, and the variable is the value of the incident surface flux density (integrated over PAR). Finally, the solution for the irradiance is simply multiplied by the gray absorption cross section to obtain the specific rate of photon absorption A = OaG (see the discussion at the end of Section 3.1). This approach allows us to obtain simple analytical solutions appropriate for such analysis. 

Parameters related to the operating conditions incident angle 9, total collected photon flux density (ie, PFD) q, and corresponding diffuse fraction Xi (here averaged over the period of exploitation). 

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