UV-visible absorbance spectra

The study of molecular complexation was then extended to other aromatic nitro derivatives125. Although, as was described before, one of the more frequent methods of studying the formation of molecular complexes is by UV-visible spectrophotometry, the author did not observe detectable differences in the UV-visible absorbance spectra between the 2-hydroxypyridine-l-fluoro-2,4-dinitrobenzene (FDNB) mixtures and the sum of their separate components. The author observed that the signals of the 1II NMR spectra of FDNB in apolar solvents were shifted downward by the addition of 2-hydroxypyridine from solutions where [2-hydroxypyridine] [FDNB] he calculated the apparent stability constants, which are shown in Table 13. 

Fig. 3.5.1 The minimum of the first derivative of UV/visible absorbance spectra of CdS particles as a function of the particle diameter. The data points have been collected from literature sources where particle sizes were determined by EM or XRD. If specific data about the minimum of the first derivative were not expressly provided, they were estimated from spectra supplied. The estimated error in this technique is less than 5 nm. For clarity, only data from groups with the greatest number of data points have been used here. A curve has been fitted to the data using a theoretical relationship between particle diameter and wavelength using the effective mass model (6). Inset Absorbance spectra of colloidal CdS produced by exposure of a CdAr film, or a Cd2+/HMP solution, to H S. The minima of the first derivative (380 nm in film, 494 nm in solution) correspond to particle sizes of approximately 2.5 nm and 6.0 nm, respectively. (From Ref. 5.)...

It is well established, mainly from UV/visible absorbance spectra, that the semiconductors formed in LB films from the reactions in Eq. (4) and (5) are in the Q-state regime. The optical properties of the generated MC and mechanistic and kinetic aspects of the reactions are discussed in a later section. 

Fig. 3.5.14 UV-visible absorbance spectra recorded while a 20-layer CdAr film was sequentially exposed to (A) dry H2S gas and then (B) wet N . In (B) the upper to lower spectra in the region between 345 and 405 nm (and the lower to upper spectra in the region above 405 nm) correspond to exposure times of 2,4, 8, 16, and 24 min, respectively. The absorbance contributions due to the quartz and the LB film have been subtracted from the spectra. (From Ref. 85.) The insets in (A) and (B) show the CdS particle diameter (from absorbance spectra) as a function of exposure time to dry H,S and wet N2. respectively.

Figure 4. UV/Visible absorbance spectra of (a) a dilute solution of lignin/polystyrene extract in toluene and (b) a saturated solution of mesy-lated lignin in toluene.

Figure8.7. UV-visible absorbance spectra of CdS particles prepared in PFPE COO-NH4+ (3 wt %) stabilized w/c microemulsions (A) Wq =10 and (B) W0 = 5 (Holmes et al., 1999a)...

Indirect Detection Methods Unique UV/visible absorbance spectra (chromophore)... 

The development of photodiode array detectors has made it possible to acquire on-line UV-visible absorbance spectra of an HPLC eluent. In contrast with older detectors, which monitored UV absorbance at only one wavelength, the photodiode array detectors monitor all wavelengths within... 

Figure 6. UV-visible absorbance spectra of compound 1 (broken line) and compound 2 (solid line).

Figure 4. UV-visible absorbance spectra of perfluorodecanethiol capped silver nanocrystals dispersed in SC-CO2 at 80 C.

Figure 5.14 UV-visible absorbance spectra of HPTS (4 x 10" M) at pH 3 (light solid line), pH 7.4 (bold solid line), and pH 10 (dashed line).

Figure 2. A) Reverse-phase HPLC chromatogram of genistein (Peak B) reacted with HOBr with daidzein as an internal standard (Peak A). Two novel peaks are shown (C and D). B) 7%e UV-visible absorbance spectra of genistein (dotted line), peak C (dashed line), and peak D (bold line).

Figure 9.26 UV-visible absorbance spectra of [Pd3(OAc)6] and n-dodecyl sulfide in a 1 5 molar ratio, respectively, dissolved in toluene. As the temperature is raised from room temperature to 95 °C, Pd nanoparticles begin to form, and the color of the solution changes from yellow to dark brown. At SOX, the solution color Is dark brown, indicating the formation of Pd nanoparticles, (a) Omin ...

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