Absorption/transmission curves

Ultraviolet Absorption/Transmission Curves of Plastic Films. 

Three 8-mil-thick cellulose acetate films containing (a) no stabilizer, (b) 0.5% UV-1A (hydroxybenzotriazole type), and (c) 1.0% UV-4 (zinc acetate dihydrate) were inserted into a Cary 17D UV/VIS/NIR Recording Spectrophotometer and their absorption/transmission curves run in the region of 250-500 nm. The film containing no stabilizer was run against air as the standard while films containing stabilizers were run against the unstabilized film as the standard. 

At concentrations of 0.25 and 0.50%, the zinc acetate behaved like the hindered-amine stabilizer—it afforded little or no photochemical protection to the wool fabric AE values of 2.47 and 2.21 were observed at the above concentrations after 550 kj/m2 exposure. Thus, one could assume it functions photochemically as an oxygen/peroxide scavenger. At concentrations of 1.0%, zinc acetate did afford moderate protection to the wool fabrics (AE value of 1.55 after 550 kj/m2 exposure), but its absorption/transmission curve exhibited a maximum absorption only at 250-300 nm. Thus, the moderate protection afforded to the wool fabric... 

Figure 24 Absorption (solid curve) and emission spectra (dotted curve) of Py and Ox in zeolite L. The dashed lines show the transmission of the Schott DAD 8-1 interference filter and the Schott OG 515 cutoff filter.

FIGURE 14-8 (a) Meaning of equivalent width, W (b) Doppler and Lorentzian line-shapes for equivalent half-widths (c) transmission curves for an absorption line for a weak and strong absorber, respectively (adapted from Lenoble, 1993). 

Fig. 11.2. Transmission of Pyrex, Vycor, and fused quartz. Transmission curves for 2-mm-lhick samples of (a) fused quariz (GE type 102), (b) Vycor (Corning 7910—note that this is a specially controlled grade the more common 7900 has an ultraviolet cutoff similar to 7740), and (c) Pyrex (Corning 7740). (Adapted from data supplied by Corning Glass Works and General I-ledlie Co.) Certain glasses and types of fused quartz are available which lack the infrared absorption at about 2.7 microns.

Alternatively, an experimental measurement can be made of the relative attenuation of a particular diffracted beam constantly set in the diffraction condition as the crystal is rotated, for example. In this case relative transmission factors can be calculated as a function of the angular setting. A different method of getting the absorption reference curve is to measure the transmission of the primary beam through the crystal this requires that the size of the primary beam is smaller than the smallest dimension of the crystal (Helliwell et al (1984b) and figure 6.3 (b)) Now for the reflection which is to be corrected, the angles of its primary and secondary beams are known. The relative transmission factors for the primary, Tp, and secondary, Ts, beams can be determined... 

In contrast to absorption spectroscopy the use of a reference is rather difficult. It requires a sample for which absorption and fluorescence spectra both exhibit the same spectral distribution as the probe. This is quite impossible. For this reason in some instrumentation one tries to eliminate fluctuations in the intensity of the light source. The excitation beam is split and a small amount of the intensity of excitation is focused on a photodiode. Nevertheless neither the changes in the optics of the instrumentation nor the variance of the transmission curve with wavelength can be overcome. However there is a way to calibrate the spectral distribution of a fluorimeter in-... 

Glass colored with neodymium shows pink to piuple colors. The corresponding transmission curve (Figure 9-17) shows absorption peaks at 570-600nm (yellow) and 530nm (green). 

Fig. 31. The calculated (blue and red curves) and experimental (points) non-linear transmission dispersion curves for the J-aggregated PIC (BioHio2-)+TBA (1 4) film (a) The calculated induced absorption (upper curve) and transmission (bottom curve) depending on the intensity laser irradiation (b)...

Addition of a blue or green tint into the plastic can also mask the yellow color. In addition to yellowing, plastics show darkening due to outdoor exposure as the transmission curve shifts downward, and there is pronounced absorption at wavelengths shorter than about 5,000 A (Figure 3.63). 

The transmission curve for the cadmium used in these experiments would actually rise more slowly as the higher energies are approached than the one shown on Fig. 8. This is because Baker and Bacher made their measurements with the neutrons incident perpendicularly on the cadmium sheet in the experiments they were incident from all angles, thus causing a greater absorption at a given energy. Thus a further correction of an unknown amount should be made which would act in the same direction as the previous correction. 

Often the combination of spectral and temporal resolution is helpfiil to simultaneously determine the individual concentrations of the different components in a mixture of pollutants, even if their absorption spectra overlap. An example is the pollution of water by different types of oil. In Fig. 10.25a the transmission curves of three different oil sorts (Diesel oil, gasoline and heavy oil) are shown and in Fig. 10.25b their emission spectra, while Fig. 10.25c shows the decay curves of the different sorts. Such measurements can help to find the polluter. In Fig. 10.26 the total fluorescence spectrum of a mixture of different aromatic hydrocarbons is shown together with the contributions of the different components, obtained by the different detection techniques discussed above [1481]. 

Fig. 1. a - dependence of diffraction efficiency (q) on phase modulation amplitude (rpi) for volume phase transmission (curve 1) and reflection (curve 2) holograms amplitude-phase transmission hologram with absorption index yo = yi = 0.1 (curve 3). b,c - intensity distribution in diffracted (solid lines) and zero (dotted lines) beams at deviation from Bragg conditions ( ) at reconstruction of transmission phase hologram (b) and transmission amplitude-phase hologram (c) at yi = Yo = 0.1 with phase modulation 1 - q>i = 0.25n, 2 -cpi = 0.75n, 3 - q>i = 1.25n, 4 - qu = 1.75n. 

Figure 10.2 Transmission curves of plates with thickness = 10 mm, for the most common optical materials bor-osilicate glass (BK7), fused silica (FS) and calcium fluoride (Cap2). Left external transmission (light reduced by the sum of internal loss tint = 1 lint) and the reflection loss Rat each surface) Right internal transmission. Note that the dips in the FS transmission curve correspond to OH absorption bands...

Figure 3.7 Transmission curves demonstrating the absorption of low-energy photons by detector dead layers and cap materials...

Optical components are manufactured from transparent materials of certain refractive indices. We have already discussed the refractive properties of glass and quartz in Sect.6.1.1. Here we will consider the transmission properties of optical materials. Optical glass is transparent from about 350 nm to 2.6 /im. This region of transmission can be extended by using quartz. In Fig.6.48 transmission curves for different qualities of quartz are shown. As can be seen the best quartz has a transmission down to 170 nm. However, strong absorption bands can occur in the near IR region, particularly at 2.7 /xm. These are due to the presence of water (O-H bonds) in the quartz. Water-free quartz can be used up to about 3.5 /xm. 

Normalized transmittance curves (verses time) for identical EB and D 1 photosensitizer concentrations are given in Figure 8.8. Due to the weak absorptivity of D 1 (see Figure 8.8(b)), the transmission curve, which, when t = 0, has a large value To - T t = 0) = 0.75, only increases by approximately 0.01. 

Fig. 6-8. Absorption curves of (A) benzene, (B) maleic anhydride (in chloroform), and (C) the benzene-MA charge-transfer complex. (D) Transmission curves for the filter. From Reference...

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