Intensity of the incident light

Nomially the amplitude of the total incident field (or intensity of the incident light) is such that the light/matter coupling energies are sufficiently weak not to compete seriously with the dark matter Hamiltonian. As already noted, when this is tire case, tlie induced polarization, P is treated perturbatively in orders of the total electric field. Thus one writes... 

Absorbance (Section 14.7) In optical spectroscopy, the logarithm of the intensity of the incident light divided by the intensity of the light transmitted through a sample A=logT0/L... 

It should be noted that in atomic absorption spectroscopy, as with molecular absorption, the absorbance A is given by the logarithmic ratio of the intensity of the incident light signal I0 to that of the transmitted light / i.e. 

We quantify transparency as the ratio between the intensity of the light that is directly transmitted through the sample relative to the intensity of the incident light according to Eq. 8.4... 

Raman scattering is a linear spectroscopy, in principle, meaning that the Raman scattering intensity, 7S, scales linearly with the intensity of the incident light, IL, provided the scattering compound can be considered as optically thin. At fixed incident light intensity IL, the Raman response scales with the population density of the scatterers, N(E) according to... 

The overall conversion efficiency (rj) of the dye-sensitized solar cell is determined by the photocurrent density (7ph) measured at short circuit, Voc, the fill factor (fif) of the cell, and the intensity of the incident light (7S) as shown in Equation (9). 

A simple measure of the number of photons entering the sample is the intensity I. The intensity of the incident light is conveniently symbolized as /c. Similarly, the number of photons leaving the sample after some is absorbed is... 

In practice, the steady-state fluorescence intensity If(7f) measured at wavelength AE (selected by a monochromator with a certain wavelength bandpass AAF) is proportional to F (/.f) and to the number of photons absorbed at the excitation wavelength AE (selected by a monochromator). It is convenient to replace this number of photons by the absorbed intensity 1a( e), defined as the difference between the intensity of the incident light 10( e) and the intensity of the transmitted light Jt( e) ... 

In practice, a multiplication factor C must be introduced to take into account the experimental conditions (total concentration, choice of excitation and emission wavelengths, bandpasses for absorption and emission intensity of the incident light, sensitivity of the instrument). 

The use of fluorescence spectroscopy in OFCD greatly improves the detection limits of the analysis. The fluorescence signal at low concentrations is directly proportional to the intensity of the incident light source and follows a general equation as... 

The intensity of an electric dipole transition in absorption or emission depends, on one hand, on factors particular to the experiment measuring the intensity, e.g., the number density of molecules in the initial state of the transition and, for absorption experiments, the absorption path length and the intensity of the incident light. On the other hand, the intensity involves a factor independent of the experimental parameters. This factor, the line strength 5(f <— i), determines the probability that a molecule in the initial state i of the transition f <— i will end up in the final state f within unit time. 

The signal measured by the photosensor expresses the intensity of the emitted fluorescence (Ip), which depends on the intensity of the incident light (/q) and sample concentration c, among other factors, such as the fluorescence (or quantum) yield (O), the molar absorption coefficient (e), and the optical path length (d). At low concentration, the intensity of emitted fluorescence is given by the following equation [33] ... 

Two-photon excitation results in an apparent violation of Beer s law. In the one-photon technique the amount of light absorbed is proportional to the intensity of the incident light. This results in emission intensity being directly proportional to the intensity of the excitation. The well-known property of two-photon excitation is that emission intensity depends on the square of the incident light intensity. 

The intensity of Rayleigh scattering is on the order of 10 times the intensity of the incident light, and the Raman intensities are at least 10 less than that of the Rayleigh scatter. Thus, the Raman effect is obviously a weak phenomenon which requires a high intensity monochromatic excitation source (a laser) and a high dispersion spectrometer with excellent stray-light characteristics to observe it. 

In all instances, the total intensity of the incident light striking a snrface, /o, is the snm of the absorbed, reflected, and transmitted intensities, Ia, Ir, and It, respectively ... 

In this equation, isc is the short-circuit photocurrent, ff is the fill factor of the cell, and I is the intensity of the incident light. 

The Beer-Lambert equation is another formalism that might describe the arrangement we have been discussing. In the Beer-Lambert equation, the intensity of the transmitted light /, relative to the intensity of the incident light 70 is given by Equation (30), which may be written... 

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