Derivative spectra, Gaussian absorption

Fig. IL The infrared absorption peak (solid line) of the ordered c(2 x 2) structure of CO on Cu(lOO) at 100 K. Shown also ate Lorentzian (dashed) and Gaussian (dash-dotted) distributions. The recorded first derivative spectrum is shown in the inset (Reproduced by permission from Ryberg. )...

A computer simulation was performed to observe the effect of variable line width on the calculated ESR first derivative spectrum. Since dipolar interaction is the major contribution to line broadening in the ESR spectrum of PVC radicals, a Gaussian line shape is expected for each of the ten absorptions. Therefore each line was assigned a Gaussian shape, the variables being relative amplitude position in the spectrum and line... 

In die Fourier transform of a real time series, die peakshapes in the real and imaginary halves of die spectrum differ. Ideally, the real spectrum corresponds to an absorption lineshape, and die imaginary spectrum to a dispersion lineshape, as illustrated in Figure 3.20. The absorption lineshape is equivalent to a pure peakshape such as a Lorentzian or Gaussian, whereas die dispersion lineshape is a little like a derivative. 

Figure 1 Experimental and simulated EPR spectra of oxidized CooA at pH 7.4. Experimental conditions temperature, 2 K microwave frequency, 35.106GHz microwave power, 20p,W 100 kHz field modulation amplitude, 0.4 mT time constant, 128 ms scan time, 4 min. Lower traces, in absorption line-shape (due to rapid-passage conditions), are the experimental spectrum (blue) and a digital integration of the simulated spectrum (red). Upper traces in first-derivative lineshape are a digital derivative of the experimental spectrum (blue) and the simulated spectrum (red). Simulation parameters component (a) g = [2.60, 2.268, 1.85], (b) g = [2.47, 2.268, 1.90] Gaussian single-crystal linewidths (half-width at half-maximum) W = [500, 200, 400] MHz. Simulated spectra for (a) and (b) are added in the ratio 2 1 to give the summed spectrum shown...

Cis-cis- TOoCl (NH3) (en) ]+ — The absorption and CD spectra in DMSO for the isomer derived from (+)5---[Co(C03)-(NH3)2(en)]+ are shown in Figure 2, where the vertical lines represents the results of the Gaussian analysis of the absorption spectrum, with labels specifying the excited states of the tetragonal components. The CD spectrum shows dominant negative peak at 16,230 cm- , which corresponds closely to the position of the... 

Fig. 9. Magnetic circular dichroism selection rules. (A) Transitions between Zeeman-split y (or S) = i paramagnetic ground (G) and excited (E) states. Right circularly polarized (RCP) and left circularly polarized (LCP) transitions are indicated. (B) MCD spectra associated with the energy scheme in (A). The dashed bands correspond to individual left and right polarized transitions, whereas the solid line spectra give the dichroism. The C-term spectrum corresponds to a Gaussian band shape, which peaks at the absorption maximum, whereas an A-term reflects its first derivative which crosses zero at the absorption maximum.

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