Differential pulse height analysis

The acquisition of the spectral information from each single spark separately is now possible with advanced measurement systems, using integration in a small capacitor and rapid computer-controlled readout combined with storage in a multichannel analyzer. With the aid of statistical analysis, sparks with outlier signals can be rejected and the precision improved accordingly. Furthermore, pulse differential height analysis enables discrimination between a number of elements such... 

The apparatus as modified for x-ray emission spectrograph is also shown in Figure 11-1. The proportional counter may be used alone (pulse-height analysis Section 2.13) or a curved-crystal spectrometer can be employed to achieve better resolution. Analytical results were comparable to those quoted above, but localization of the area analyzed was considerably less sharp than the micron-diameter spot achieved in differential absorptiometry. 

Observations of atmospheric nanoparticle number concentrations have increased greatly during the last five years. This advance has been made possible by new instruments and techniques that can measure particles with diameters as small as 3 nm. The new approaches include pulse height analysis of data from an ultrafme condensation particle counter (UCPC) (Stolzenburg and McMurry 1991 Wiedensohler et al. 1994 Weber et al. 1998b) and the combination of a nano-differential mobility analyzer (nano-DMA) (Chen and Pui 1997 Seto et al. 1997) with a UCPC. 

As in the case of differential double potential pulse techniques like DDPV, slow electrochemical reactions lead to a decrease in the peak height and a broadening of the response of differential multipulse and square wave voltammetries as compared with the response obtained for a Nemstian process. Moreover, the peak potential depends on the rate constant and is typically shifted toward more negative potentials (when a reduction is considered) as the rate constant or the pulse length decreases. SWV is the most interesting technique for the analysis of non-reversible electrochemical reactions since it presents unique features which allow us to characterize the process (see below). Hereinafter, unless expressly stated, a Butler-Volmer potential dependence is assumed for the rate constants (see Sect. 1.7.1). 

Figure 4.28 Multichannel analysis produces a histogram of counts against channel number - a differential pulse height spectrum...

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