Pulse methods, advantage

Verma and Kaliaguine [339] measured the reaction rate using the pulse technique. They found good agreement with the data of Table 2, obtained for stationary conditions. The authors gave a clear presentation of advantages and disadvantages of the pulse method. 

Eletrochemical detection has been used for the detection of synthetic dyes. Fogg et al. (226) described a method for the qualitative and quantitative determination of several synthetic dyes using polarographic detection. The system was a stationary mercury drop electrode operated in the differential-pulse mode. Ashkenazi et al. (131) used fast-scan square-wave voltammetry for the polarographic detection of five synthetic dyes. The voltametric mode was observed to be much faster than the differential-pulse method. Another advantage is that the experimental measurement produces, in addition to the peak current, the redox potential of the dye, which can serve to identify the analyte further. 

According to the above, the electrochemical response in the different differential pulse techniques can be very different, and it is worth analyzing the advantages and disadvantages of each method. Regarding the double pulse methods, in normal mode, DNDPV, this has the inconvenience of presenting asymmetrical peaks that can hinder the experimental determination of the peak current. In addition, the peak... 

Potential step methods have emerged as valuable electrochemical methods due to the highly sensitive nature of the technique. The waveform employed in potential step methods, also referred to as pulsed methods, have some advantages over potential sweep methods. The main advantage is that the steplike waveform can discriminate and separate the capacitive current versus the faradaic current, the current due to the reduction or oxidation undergone by the analyte, increasing signal to noise. Capacitive versus faradaic current discrimination is the basis for all of the pulsed techniques. The rate of decay of the capacitive current and the faradaic current is not the same. The capacitive current has an exponential decay whereas the faradaic current decays as a function of t Since the rate of decay of the capacitive current is much... 

The dependence of HETP upon solution flow rate when exchanging the H -Na pair of ions between 0.2 M chloride solution and cation exchanger, KU-2 x 8, with beads 0.25-0.50 mm in diameter, has been compared in the literature for columns of different types [76,84]. The pulse method which has been used possesses the advantage that with the pulsed injection of a small amount of substance all physicochemical and hydrodynamic characteristics of the system remain invariably determined by the primary substance, Na" " ion in this case. Dynamic parameters obtained characterize the process when the concentration range of impurity is low. 

The most satisfactory experimental methods are (a) analysis of potential relaxation after current interruption from a prior steady-state potentials and (b) ac impedance spectroscopy at steady-state potentials. These methods have been referred to in Section VI. They both have the advantages that no H2 reoxidation occurs and no surface oxidation of the electrode takes place, as can arise in the current pulse method (121). The principal applications of the potential-relaxation method to determination of OPD H have been in the work of Bai and Conway (75) on H adsorption in the HER at Ni, Ni-Mo composites, and Pt (136), and by Conway and Brousseau (162) at bulk, single-phase Ni-Mo alloys (Mo 0 to 19 at%). 

Major results. The method is useful for control of expensive materials in responsible applications, such as, for example, materials used in aeronautics. Material control or inspection can be conducted (pulse method) without damage caused to the inspected material. The other essential advantage of the method is related to the fact that fillers can be observed within the filled material, which is not possible by any other technique. In addition, clarity of the micrograph is improved compared with optical microscopy. This method, although unique, has many applications in filled materials and hopefully more data will be known in the future in order to facilitate better understanding of filled materials. 

The tast method (6, 36-38) is considered here not because it is widely practiced, for it makes sense only with the DME and it holds no advantages with respect to more advanced pulse methods, but because this method furnishes a useful starting point for understanding the sampling strategies that are integral to pulse voltammetry. 

An advantage of the probe-pulse method is the fact that the excitation and detection are completely decoupled. Therefore, there is no instrumental deadtime. Furthermore, sensitive optical detection is used and in a few favorable cases the spin coherence of only 10 excited molecules could still be detected. 

As already mentioned in context with the mechanical system, the advantage of the pulse methods is generally the easier handling of systems with more than one eigenfrequency. Let us consider as an example a system with two different kinds A and BX of nuclear spins I = V2 which are coupled together. We assume that a rt/2 pulse has been applied to the nuclear spins A. Then, the free induction decay of the magnetization of the A system in the rotating frame can be written instead of Eq. (30) as follows - ... 

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