Optical derivative

OS 94][R 13][P 74]ForadmixtureofsampleswifhvaryingconcentrationsofCo(ll) and Cu(II), the respective changes in the Co(ll) chelate complex concentration as a function of contact time were optically derived [28]. Analysis was performed in the reaction/extraction area and also in the decomposition/removal area (Figure 4.102). As expected, more complex is formed in the reaction/extraction area with increasing contact time. Also, more complex results when increasing the Co(ll) concentration at constant Cu(ll) concentration. This proves that mass transfer is efficient (as high concentrations can also be handled) and that no interference from other analytes falsifies the measurement. As a result, calibration curves were derived. 

GL 27] [R 3] ]P 29] By means of sulfite oxidation, the specific interfacial area of the fluid system nitrogen/water was determined at Weber numbers ranging from lO " to 10 [10]. In this range, the interface increases from 4000 m m to 10 000 m m . The data are - with exceptions - in accordance with optically derived analysis of the interface and predictions from calculations. At stiU larger Weber number up to 10, the specific interfacial area increases up to 17 000 m m, which was determined optically. 

Fig. 4 Comparison of optically derived Ay values with UB3LYP/6-31 + G -calculated A v values,24 82 and with experimental intermolecular intrinsic barriers for 360/+-380/+.

Fig. 5 Plot of optically derived Xs in acetonitrile versus number of bonds between the hydrazines for phenyl, ter -butyl-substituted IV radical cations. The circles show saturated-bridged compounds, and the squares aromatic-bridged ones.

To compare with ESr, we calculate rate constants using the optically derived quartic-fitted parameters with the following rate expression ... 

Figure 5 Enhancing the minute differences of analytes with very similar absorption spectra using optical derivative spectra. (Reprinted with permission from Vogt F, Tacke M, Jakusch M, and Mizaikoff B (2000) An ultraviolet spectroscopic method for monitoring aromatic hydrocarbons dissolved in water. Analytica Chimica Acta 422 187-198 Elsevier cf. Erratum (2001) Analytica Chimica Acfa431 167.)...

The approximation made in the third line of [16] is acceptable for several applications and simplifies experimental setups for measuring optical derivatives... 

Because numerical derivatives are computed from spectra, which are measured with a broadband amplifier, noise at all frequencies affects the measurement spectra. Optical derivatives, however, utilize a DC amplifier with a high time constant and lock-in amplifiers with narrow bandwidth boa. Only noise with frequencies qj + 5co/2 and Ico + bcojl influences the first and second derivatives. The DC measurement can only be affected by long time drifts - AC noise is averaged out. This improves the signal-to-noise ratio compared to the numerical approach. 

J. M. Raimundo, P. Blanchard, N. GaUego-Planas, N. Mercier, 1. Ledoux-Rak, R. Hierle and J. RoncaU, Design and synthesis of push-puU chromophores for second-order nonUnear optics derived from rigiditied thiophene-based jt-conjugating spacers, J. Org. Chem., 67, 205-218 (2002). 

This section will provide a basis for understanding the optical effects to a reader who is not familiar vith optics. Derivations will not be given. For a deeper, accurate and quantitative understanding the reader is referred to textbooks on electrodynamics... 

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