Solar spectrum irradiance

Wavelength range—start, stop, mean radius vector correction, integrated solar spectrum irradiance WLMN, WLMX, SUNCOR, SOLARC... 

Fig. 9.7 The J-V curves of DSSCs containing liquid electrolytes, Poly(St-AN), [PBvim][Br], and [PBvim][N(Tf)2]-based electrolytes (polymer contents 25 wt%) (a) Under simulated AM 1.5 solar spectrum irradiation at 100 mW cm". (b) In the dtnk [101]...

Sarina S, Zhu H-Y, Xiao Q, Jaatinen E, Jia J, Huang Y, Zheng Z, Wu H (2014) Viable photocatalysts under solar-spectrum irradiation nonplasmonic metal nanoparticles. Angew Chem Int Ed 53 2935-2940... 

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. 

Figure 1. Production of Fe(II) on irradiation of pH 4.0 solutions of distilled, deionized water and 0.1M NaCl and a pH 6.5 solution of 0.1M NaCl/2mM NaHC03 containing 3.5pM am-FeOOH. The ultrafilterability of the iron through a membrane exhibiting a nominal molecular weight cutoff of 10,000 (Amicon PM10) in the pH 4.0 study is also shown. Light source simulated solar spectrum of total intensity 300 pEinsteins cm-2 min-1. (Reproduced from Ref. 32. Copyright 1984, American Chemical Society.)...

The HOMO-LUMO gap of the photosensitiser determines the current produced on irradiation. The smaller the size of this gap, the larger the photocurrent, due to the ability of the dye to absorb longer-wavelength regions of the solar spectrum. 

Small differences in light sources have definite effects on photochemical processes. Some irradiation systems match the solar spectrum poorly, thus affecting the relative importance of the various photodissociation processes occurring in the atmosphere. Ambient variations in the nitrogen dioxide photolysis pseudo-first-order rate constant,... 

Solar spectrum on the earth ranges from 250 to 2400 nm, having its maximum at 500 nm. The energy abundant ultraviolet region below 400 nm contributes only 5 % the visible region between 400 and 800 nm occupies about half the spectrum. The conversion of this visible irradiation is therefore important. 

As mentioned, the photocatalytic activation of Ti02 requires UV irradiation, and hence the semiconductor performance in the solar spectrum is inefficient. A solution to switch the photocatalytic activity to the visible spectral region was described by covalent attachment of an eosin dye monolayer to the semiconductor oxide particles of a Pd-Ti02 catalyst.168 The improved photocatalytic activities, specifically, the efficient formation of formate, are attributed to the effective injection of electrons from the excited dye into the semiconductor conduction band. 

The handsheets impregnated with quinone model compounds were photolyzed in an Oriel 1000 W Solar Simulator. The Solar Simulator uses a xenon arc lamp to simulate the solar spectrum and was fitted with an air mass 1.5 global filter to model the average wavelength distribution of solar irradiation in the continental United States. An exhaust fan provided air circulation to minimize heating of the sample. The spectral distribution of the solar simulator is approximately equivalent to natural sunlight. 

Light Exposures. Silk fabric samples, 0.25 m x 0.17 m, were mounted in Atlas Electric Devices aluminum sample holders according to AATCC Test Method 16E-1982 (7). An Atlas Ci-35 Weather-Ometer xenon-arc was used on continuous light cycle. Exposures were conducted at an irradiance of 0.35 W/m2 measured at 340 nm and the irradiance was monitored and controlled automatically. Borosilicate inner and outer filters were used to simulate the solar spectrum. The relative humidity was maintained at 65% and the black panel temperature was 50°C. The actual fabric temperature during the irradiation was measured, using small thermocouples threaded into the fabric, and was found to be 35 C. Control samples for these tests were kept in the dark at 35°C and 65% RH for the same time period as the illuminated samples. 

The spectral dependence of the light sensitivity (as indicated by yellowing) of free films of Parylene-C was determined. A Heraeus Sun-Test chamber, equipped with a xenon arc lamp filtered to yield a simulated solar spectrum, was used for the irradiation. An additional infrared filter minimized sample heating. The irradiance at the sample location was originally 0.83 W/m2 at 340 nm, but the output decreased approximately 20% after 1500 hours use. Long band-pass optical filters with nominal cut-offs of 305 nm, 345 nm, 385 nm and 400 nm were inserted between the xenon lamp and the Parylene-C film samples to determine the wavelength threshold for yellowing. The sample temperature was maintained at 30+ 2 °C with a water-cooled... 

The most direct way to carry out the measurements is in places where the measured solar spectrum is found to be nearly identical to the standard AM1.5G spectrum. By measuring the temperature dependence and irradi-ance dependence of the I/V curve parameters, cell properties may be adjusted to the SRC. Since in most places around the world these SRC conditions cannot be met, characterisation laboratories have been set up with suitable apparatus and procedures to do accurate indoor efficiency measurements under SRC according to international standard norms (ASTM, IEC). This involves... 

Fig. 3 The solar irradiance from X = 1 nm to X = 0.1 mm and normalized black-body radiation for T = 5770 K. Solar irradiance data are from SOLAR2000 http //www.spacewx.com/ solar spectrum.html for 8 February 2002...

Fig. 7. The solar irradiance (mW cm 2 nm ) in the figure inset, and the total insolation power (mW cm-2) in the main figure of the solar spectrum 3 see also Chapter 2.

Radiometric quantities are important to describe and measure UV and VUV radiation. They are usually subdivided into energetic, spectral and photonic terms. Energetic terms (Tab. 3-9) are based on the energy of the radiation and they refer to all relevant wavelengths. Eor each of these terms a spectral derivative can be defined (Bolton, 1999) which is correlated with a specific wavelength X. Eor example, the extraterrestrial solar spectrum incident on the upper atmosphere is represented by the mean spectral irradiance Eq in W m nm over a defined wavelength interval AX in nm (CIE, 1989). Further, each of the spectral units can easily be transferred to photon-based units, which themselves are related to radio-metric units (cf Braun et al., 1991). 

El 1000 W m is the standardized irradiance based on the AM 1.5 standard solar spectrum on a horizontal surface. 

A second characteristic of UV solar radiation is fhat, even for very clear afmospheres, if is composed in similar amounfs of both beam and diffuse radiation (Hulstrom et al., 1985). The first is defined as the radiation arriving directly from the sun, while the second is the solar radiation that has been scattered by gases and aerosols after entering the earth s atmosphere. This second t)/pe of radiafion reaches fhe ground in a more or less diffuse manner that is, with similar intensity from all directions in the sky. In this respect, the situation encountered in solar photocatalytic reactors is quite different from fhe one encounfered in solar fhermal collectors. The latter are able to use the whole solar spectrum, and in that case diffuse radiation accounts for a much smaller fraction of fhe global irradiance. 

Figure 2. Irradiation wavelength spectra in Suntest CPS andXXL- in comparison to the terrestrial solar spectrum.

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