Time amplitude measurements, detection method

Some representative spectra are displayed in Fig. 4. We have found that the ARES G2 rheometer is approximately 2.8 times more sensitive than the ARES G1 rheometer under optimized conditions using the identical detection method (external recording. Fig. 4a). Furthermore using the manufacturer s software TRIOS to record the time data (method C) resulted in a factor of 40 improvement in sensitivity compared to recording of the raw shear stress in the time domain (method B) as shown in Fig. 4b. With method C, a spectrum with S/N of could be achieved. It can be inaeased to S/N 10 by averaging more cycles per amplitude (Fig. 4c) which of course prolongs the total measurement time... 

The principle of this pulse method and its general equations are easily extended to the case of several components in a mixture. The method was used by Lindholm et al. [24] to determine the quaternary isotherms of the enantiomers of methyl- and ethyl-mandelate on the chiral phase Chiral AGP. One of the serious roadblocks encountered in the use of the pulse tracer method is that the amplitudes of most of the system peaks decrease rapidly when the plateau concentration increases. Since the signal noise increases in the same time, it becomes rapidly impossible to make any accurate measurements of the retention time of these peaks. On the basis of fundamental work by Tondeur et al. [114], the origin of this variation of the relative intensity of the system peaks was explained by Forss n et al. [47], who then derived an effective rule to determine the composition of a perturbation pulse that generates system peaks that are detected easily. The concentrations of the components in the injected perturbation pulse should... 

A time-to-amplitude converter (TAC) system was also employed to measure fluorescence decays without the microscope. Then, the fluorescence decay and the fluorescence lifetime were obtained precisely with the microchannel-plate photomultiplier (MCP-PM) as detection. The time resolution of the lifetime was determined, using a convolution method, to be 10ps. 

After a first paper in 1988, " Bretthorst paved the way for the application of Bayesian probability theory (BPT) in a series of three papers.- The first presents the connection between the theory and the case of NMR phenomena and discusses parameter estimation and detection of quadrature signals. The second " shows the ability of Bayesian methods to measure the quality of a model. The third " provides examples of applications to experimental data where decaying sinusoids are assumed. A fourth paper, produced during the following two years, discusses computer time requirements and noise, and it is shown to be important to include knowledge in the analysis," " while a fifth publication is devoted to amplitude estimations for multiplets of well-separated resonances. 

While the single-pulse methods described above are widely used, another approach is to apply the perturbation as a sine wave, in which the response will be in the form of another sine wave lagging consistently behind the perturbation to a degree related to the relaxation time of the system. The frequency of the applied perturbation is critical if it is too slow, then the chemical response will catch up and no lag will be detected, but if it is too fast the chemical response will never attain a measurable amplitude before it must change direction. Only... 

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