Absorbance triangle

The absorbance diagram of the stilbene photoreaction is shown schematically below. Since the flrst step is an equilibrium, the absorbance line from c/.r-stilbene to phenanthrene does not form a tangent to the measured absorbances. The point B is determined from the absorption coefflcients of the c 5-stilbene at both the wavelengths 250 and 292 nm and the initial concentration Oq. Point C is obtained by the absorbance coefficients of phenanthrene and the initial concentration of fra/u-stilbene. The lines JITai b Kq correspond to the calibration curves for the three reactants absorbance/ concentration. 

The triangle can be considered as a vector space, given by u, v, Vj. Using these vectors the concentrations of all the reactants can be obtained for each reaction time according to 

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Fig. 5.15. Schematic E-diagram for the reaction A B C, including an absorbance triangle according to a distorted Gibbs phase diagram.

Fig. 10-8. Single particle scattering to mass ratio for particles of four different compositions. Carbon particles are also very efficient absorbers of light. Source U.S. Environmental Protection Agency, "Protecting Visibility," EPA-450/5-79-008, Office of Air Quality Planning Standards, Research Triangle Park, NC, 1979.

If one wants to understand why such changes occur, one can look at a few of the basic equilibrium properties of such complexes. Figure 1 illustrates the trends which occur when a sample is titrated with copper, monitoring three different parameters. The black dots indicate the relative amount of bound copper as indicated by free copper ions sensed with an ion-selective electrode (Xc of left ordinate). The triangles represent the change of the absorbance of the solution at 465 nm (right ordinate). The curve with the open circles is the relative quenching of the fulvic acid fluorescence (Q of left ordinate). We see that we are able to probe several different types of sites with different types of probes for this multidentate system. 

Figure 2.8 Amounts of P absorbed by a planar resin sink in contact with columns of soil that was flooded (circles), moist (triangles) or flooded then moist (squares). Lines are fits to Equation (2.22) (Huguenin-Elie et al, 2003). Reproduced by permission of Blackwell Publishing...

Fig. 10 Ratio of UV absorbances vs solvent polarity. Squares represent solvents which bring about a folded or partially folded conformation. Triangles represent denaturating solvents (CHCI3, CH2CI2,1,2-dichloroethane). The overall trend of increased folding nature in more polar solvents is evident...

Figure 2 Photon energy dependence of the yield of ssb (open circle) and dsb (closed circle) per absorbed energy in plasmid DNA irradiated in aqueous solution [44]. The Fricke yield is also shown for comparison (closed triangle).

Fig. 3.5.7 Absorbance (corrected for ArH and the quartz substrate) of 10-layer (solid line), 20-layer (dashed line), 30-layer (triangles) and 40-layer (squares) HgAr films exposed to H2S for 15 min. Inset Absorbance of HgS in ArH (corrected for ArH and quartz) as a function of layer number at 350, 400, 500, 600, and 700 nm. (From Ref. 45.)...

Figure 3. A composite spectrum of SN 1987a observed on March 1 (Danziger et al. 1987) is compared with one of our best-fitting (absorbed) computed spectra, corresponding to the parameters indicated. Both the theoretical spectrum (triangles) and that of an (unabsorbed) blackbody at the same effective temperature have been displaced by the same amount for clarity (see separate scales). No theoretical points are shown at wavelengths shorter than that at which the other stars dominate the flux.

Fig. 3.12 Time course of absorbance of MG solution in the presence of slide glass (triangles) or HyCOM-film-A (circles). 1...

Figure 9 Aerosol attenuation factor I) (A)= 1- F er (A)/ Fckjr (A) at 325 nm for nonabsorbing (triangles) and absorbing (diamonds) aerosols as a function of the TOMS Lambert-equivallent reflectivity (R-0.05)/0.9 (the true surface reflectivity Rj= 0.05). Solar zenith angle is 50°, satellite zenith angle 32° and azimuth 90°...

Fig. 9.8. Determination of die molar coefficients of absorbance of (i )-4 (circles, absorption maximum 1751 cm-1) and (S)-l3C-4 (triangles, absorption maximum 1699 cm-1) by linear regression [22].

Figure 9 shows the results of oxidation experiments in a case where only normal CO was chemisorbed. The absorbances are indicated by triangles (A) and the wavelengths by squares (B). 

AATCC Test Method 79 Absorbency of bleached fabrics, AATCC Technical Manual, American Association of Textile Chemists and Colorists, Research Triangle Park, NC, 1999, 102. 

Figure 5 Gel permeation separation of Needless Eye humic substances, showing dEtribution of U radiotracer (circles) and (triangles) between fractions. concentration 1500 mg kg concentration 500 mg kg pH 8-9 I = 0.1. UV absorbance at 465 nm is used as an indicator of organic matter concentration.

Fig. 8.7 (a) In vitro phosphorylation inhibition assay for Abl enzyme in the presence of WBZ 4 (squares) or imatinib (triangles). Active recombinant Abl enzyme (1 (Jig/ml) and its substrate (Abl-tide, 1 p.g/ml) were incubated for 1 h at 37°C in the presence of various WBZ 4 or imatinib concentrations. ATP (100 nM) was added to the reaction mixture. Phosphorylation of Abl-tide peptide was detected by incubation in consecutive order with antirabbit phospho-Abl-tide antibody and antirabbit horseradish peroxidase (HRP) antibody. Phosphorylation of the substrate was quantified as absorbance units (AU) by spectrophotometry at 450 nm. Values obtained with the enzyme without the inhibitors (WBZ 4 or imatinib) were assumed to be 100% phosphorylation and were compared to the values obtained with the addition of the inhibitors, (b) In vitro phosphorylation inhibition assay for C-Kit in the presence of WBZ 4 (squares) or imatinib (triangles). Active recombinant C-Kit kinase (25 ng/ml) and its substrate poly (Glu4-Tyr, 150 nM) were... 

Figure 4 Water decomposition yield, G(-HO), as a function ofthe flux ratio alpha/y irradiation (mixture of high and low LET particles). Increasing this ratio means increasing the LET value. The observed decomposition threshold Is shifted to the right (higher LET) and disappears betwen. 30 °C and 200 °C. The scale corresponds also to the concentration In °B. The difference between circle and triangle symbols Is the Initial enrichment In °B In the chemicals. Adding °B that absorbs neutrons under neutron/gamma Irradiation produces alpha rays having high LET (200 eV/nm) [6],...

Fig. 10. The distribution diagram of the species present at the equilibrium in a solution containing equimolar amounts of Ni(II) and of the heteroditopic ligand 6 (% concentration in the left vertical axis). Relevant species to the translocation process are [Ni(II)(LH2)]2+, 90% at pH = 7.5, in which the Ni(II) center occupies compartment B, and [Ni(II)(L)], 100% at pH > 9.5, in which Ni(II) has moved to the doubly deprotonated A2- compartment. When in the A2- compartment, the Ni(II) center shows a square-planar stereochemistry (low-spin, yellow, d-d absorption band at 450 nm, s = 103 M-1 cm-1) full triangles indicate the variation with pH of the intensity of such an absorption band (molar absorbance on the right vertical axis)...

Figure 8. The time evolution of absorbance at 370 nm exhibited by reduced AgPFSA films exposed to air. The different curves correspond to membranes prepared after 9 (filled triangles), 14 (open circles), 19 (open squares), 23 (open triangles) and 24 (filled circles) hours of exposure to H

Here r.. is the distance between atoms i and j, f,(co) and f.(9) are the scattering amplitude, which now depend on the angles in the triangle which joins the absorbing... 

Rtot= n+ry+rj total length of the triangle composed by the absorbing atom and the i-th andj-th atoms. 

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