Fluorescent before irradiation, intensity

Figure 7. Variation of carbonyl index vs. time of irradiation in a Xenotest-150 weatherometer (50% RH 45°C) for different batches of commercial polypropylene. Before irradiation the samples had relative fluorescence intensities at 340 nm of (A), 1.0 ( , ), 0.73 ( , A), 0.44 (O), 0.25. EX Amax = 230 and 285 nm.

C, however, and then recooled, the ratio of zinc to sulfur is found to increase very slightly ultraviolet irradiation of this sulfur-deficient product produces an intense blue fluorescence. Further, if one thousandth of 1-percent CuS is thoroughly mixed in with the ZnS before heating, irradiation of the cooled product produces a green fluorescence that persists after the radiation has been removed (phosphorescence). 

A solution of the high-cis polymer fluoresces when excited by irradiation at 330 nm. The initial spectrum displays a weak emission at about 370 nm attributed to 2% of tra s-stilbene segments originally present in the chains. With continued irradiation (2 min) there is an increase in the emission from this band as more trans double bonds are generated, and a new emission appears at 445-500 nm. After further irradiation, this intense red-shifted luminescence becomes the predominant feature before the polymer precipitates. In a statistical copolymer of 9% of 71 and 91% of norbomene, the units of 72 are isolated between norbomene units, and the fluorescence spectrum is confined to the shorter wavelength region with a maximum around 360 nm (Miao 1994a). 

FIGURE 35.3 Fluorescence intensity = 450 nm) of 10 oM folic acid (FA) in the absence or presence of p-LG, bovine serum albumin (BSA), or a-lactalbumin (a-LA) before and after 110 min of irradiation at an excitation wavelength of 348 nm (protein concentration is 20 pM). (Reprinted from Food Chemistry, 141(2), Liang, L Zhou, P., and Subirade, M., Protective effect of bovine serum albumin, p-lactoglobulin and a-lactalbumin on photodegradation of folic acid, 655-1572. Copyright 2013, with permission from Elsevier.)... 

Figure 4. shows part of the fluorescence data from idiich figure 3. was calculated Whilst in D. purpurea there is a significant dip in the fluorescence (Fg) following the decrease in irradiance before the level recovers, this dip is absent in C album. Such a dip can be induced by using a more intense hi light... 

---