Spectrum absorption solar

In 1817, Josef Fraunhofer (1787-1826) studied the spectrum of solar radiation, observing a continuous spectrum with numerous dark lines. Fraunhofer labeled the most prominent of the dark lines with letters. In 1859, Gustav Kirchhoff (1824-1887) showed that the D line in the solar spectrum was due to the absorption of solar radiation by sodium atoms. The wavelength of the sodium D line is 589 nm. What are the frequency and the wavenumber for this line ... 

Fig. 3. The absorption spectrum for solar radiation in the Earth s atmosphere 19X On the ordinate is plotted the altitude at which the radiation intensity is reduced by a factor e 1 from its unattenuated value. The species predominantly responsible for the absorption in the various wavelength ranges are as indicated. The wavelength of the H Lyman-a radiation closely coincides with a window in the O2 absorption spectrum...

The atmosphere absorbs radiation quite selectively in narrow-wavelength bands. The absorption for solar radiation occurs in entirely different bands from the absorption of the radiation from the earth because of the different spectrums for the two types of radiation. In Fig. 8-65 we see the approximate spectrums for solar and earth radiation with some important absorption bands... 

Diamond et al. [127] have estimated UVR doses in wetlands using this approach. Typical UVR doses were estimated by first generating maximal solar radiation doses for each day using a radiative transfer model, SBDART [113]. The model produced values for the full spectrum of solar radiation, from 280 to 700 nm, for cloudless conditions. These maximal values were then modified based on cloud cover effect estimates from 30 yr of historical solar radiation data (National Renewable Energy Laboratory, Department of Energy http //rredc.nrel.gov/solar/). The values derived in this procedure were estimated daily terrestrial, spectral (2 nm increments from 280 to 700 nm) solar radiation doses. Water column doses were then derived from absorption coefficients and spectral attenuation data described by Peterson et al. [128]. Although the focus of this effort was to characterize risk of UV-B radiation effects in amphibians, the procedure is directly applicable to phototoxicity, and the resulting UV-A radiation and spectral doses could be directly incorporated into calculation of possible effects. 

Vasudev R., Absorption spectrum and solar photodissociation of gaseous nitrous acid in the actinic wavelength region. Geophys Res. Lett 17, 2153, 1990. 

The spectrum of solar radiation reaching the top of the earth s atmosphere is close to the black-body radiation curve for an emitter at 5,520 K. Absorption and scattering in the atmosphere decrease the apparent temperature to about 5,200 K at sea level. The overall entropy change (ASa + ASr) associated with photoexcitation here is, therefore, on the order of 0.25hv/ 300 K) — hv/ 5,200 K) = 0.20/iv/(300 K). 

Since the absorption spectrum, absorption cross sections, and photolytic processes in the tropospheric solar actinic flux region, and photolytic quantum yields have already been described in detail in the Sects. 3.2 (Fig. 3.6) and 4.2.1 (Fig. 4.2,4.3,4.4, 4.5, 4.6, 4.7, and 4.8, Table 4.1, 4.2,4.3, and 4.4), only photolytic processes in the stratosphere will be described here. As seen in Fig. 3.6, the absorption spectrum of the Hartley bands of O3 extend over broad range of 200-300 nm that is the most important in the stratospheric solar actinic flux. The photolytic process of O3 molecules reached by the absorption of photons in the Hartley bands is thought to be... 

Molecules and atoms interact with photons of solar radiation under certain conditions to absorb photons of light of various wavelengths. Figure 10-4 shows the absorption spectrum of NO2 as a function of the wavelength of light from 240 to 500 nm. This molecule absorbs solar radiation from... 

Room-temperature fluorescence (RTF) has been used to determine the emission characteristics of a wide variety of materials relative to the wavelengths of several Fraunhofer lines. Fraunhofer lines are bands of reduced intensity in the solar spectrum caused by the selective absorption of light by gaseous elements in the solar atmosphere. RTF studies have recently included the search for the causes of the luminescence of materials and a compilation of information that will lead to "luminescence signatures" for these materials. For this purpose, excitation-emission matrix (EEM) data are now being collected. 

Tetrachlorodibenzo-p-dioxin (TCDD) (I), an occasional contaminant in 2,4,5-T and other trichlorophenol derivatives, is the most toxic of the commonly-encountered dioxins (8) and it received most of our attention. Its low solubility in common solvents and water (ca. 2 ppb) limited our experiments since the products were difficult to identify by the conventional techniques of organic chemistry. However, TCDD has an absorption maximum at 307 nm in methanol—well within the solar spectrum observed at the earth s surface and near the region of maximum intensity (310-330 nm) of the UV lamps used in previous experiments (H 29). 

The photochemical activity of pure Ti02 has been invesli ted extensively for decades, and it has been revealed that the primary limitation is poor solar spectrum photon absorption because of its wide band gap. Recently, it has been reported that narrowing band p,p can be achieved by doping TO2 with other elements such as nitrogen[7], sulfiir, caibon, etc. For example, fliara et al.[8] reported nitrogen doping shifts the absorption band as well as narrows the band gap. 

The case of water is particularly convenient because the required high Ka states may be detected in the solar absorption spectrum. However, it is difficult to observe the necessary high vibrational angular momentum states in molecules, which can only be probed by dispersed fluorescence or stimulated emission techniques. On the other hand, it is now possible to perform converged variational calculations on accurate potential energy surfaces, from which one could hope to verify the quantum monodromy and assess the extent to which it is disturbed by perturbations with other modes. Examples of such computed monodromy are seen for H2O in Fig. 2 and LiCN in Fig. 12. 

The short circuit current is the product of the photon flux (A.) of the incident solar spectrum and the wavelength-dependent spectral response or collection efficiency Q( k) integrated over all wavelengths 7sc = / k)Q k)dX (see Fig. 61b). The collection efficiency is about 80% between 450 and 600 nm, demonstrating that there is little loss due to recombination (the i-layer is of device quality). The decreasing collection efficiency at the red side is due to the decreasing absorption coefficient of a-Si H. In the blue, the decreasing collection efficiency is due to absorption in the /7-layer and/or buffer layer. 

The rate of photolytic transformations in aquatic systems also depends on the intensity and spectral distribution of light in the medium (24). Light intensity decreases exponentially with depth. This fact, known as the Beer-Lambert law, can be stated mathematically as d(Eo)/dZ = -K(Eo), where Eo = photon scalar irradiance (photons/cm2/sec), Z = depth (m), and K = diffuse attenuation coefficient for irradiance (/m). The product of light intensity, chemical absorptivity, and reaction quantum yield, when integrated across the solar spectrum, yields a pseudo-first-order photochemical transformation rate constant. 

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