Single-pulse experiment

Single pulse experiments, as shown in Fig. 6.2-27, may be performed at different stages of conversion during a polymerization reaction. Analysis of the measured U versus t curves provides a very detailed picture of the polymerization kinetics, e.g., of rate coefficients as a function of monomer conversion (Buback, 1991). 

Henrici et al. [504] carried out a shock tube study of the CO + F2O reaction in mixtures heavily diluted with argon at higher temperatures. They obtained data on overall CO2, O2 and COF2 production from single pulse experiments, and they also made time-resolved optical measurements of the rate of formation of CO2 and depletion of F2O by studying the emission at 4.3 pm and the absorption at 2200 A, respectively. The major path for the decomposition of F2O was assumed to be by reactions (xcii)—(xciv)... 

Reported in Fig. 6 is the normalized fomiation of maleic anhydride (in the sub-second range) in single pulse experiments with an n-pentaney02 f ed on a dean PVO surface (a) and on a PVO... 

In the single-pulse experiments described up to this point, a 90° pulse is followed by a period during which the free-induction decay is acquired (Figure 6-1 a). Fourier transformation of the time-dependent magnetic information into a frequency dimension provides the familiar spectrum of 8 values, henceforth called a one-dimensional (ID) spectrum. 

Different approaches were used to distinguish between the signals of guest and host molecules. In single-pulse experiments (SPEs), with a relatively short delay of 8-10 s, only solvent C resonances were monitored (Fig. 20a, and top trace Fig. 20c,). This so-called T discrimination experiment takes advantage of the significant distinction of the spin-lattice relaxation times of the mobile... 

As described in Chapter 6.5 the Henry coefficient can be determined by single pulse experiment at low concentrations of component A. 

Figure 3. Results of single-pulse experiment. Pulsing CO over partially oxygen covered platinum (573 K). CO pulse given after 3 cycles of CO pulse followed by O pulse over initial fully O-covered platinum.

The approach to any structural or mechanistic problem will invariably start with the acquisition of one-dimensional spectra. Since these provide the foundations for further work, it is important that these are executed correctly and full use is made of the data they provide before more extensive and potentially time-consuming experiments are undertaken. This chapter describes the most widely used one-dimensional techniques in the chemistry laboratory, beginning with the simple single-pulse experiment and progressing to consider the various multipulse methods that enhance the information content of our spectra. The key characteristics of these are summarised briefly in Table 4.1. This chapter does not cover the wide selection of techniques that are strictly one-dimensional analogues of two-dimensional experiments, as these are more appropriately described in association with the parent experiment and are found throughout the following chapters. 

The amount of N 0 formed is much higher than the amount formed in the single pulse experiments over an oxidised surface. At 573 and 673 K about 50 % of the outcoming NO is detected as N 0. At 513 K 30 % of the outcoming NO is detected as N 0. As the pump/probe pulses are cycled for signal averaging the surface will be partly reduced in this experiment. This result clearly demonstrates that on a partly reduced platinum surface NO will... 

Set the well shimmed NMR instrument for a single-pulse experiment, and determine the pulse width by systematic variation that is, determine the time necessary for a 360° pulse—after obtaining a 360° pulse the spin system is returned to its starting condition and no NMR signal should be found in the Fourier-transformed spectrum. (This condition is usually the easiest to observe.) Then find the 180° and 90° pulses by dividing the time for the 360° pulse by 2 and 4, respectively. 

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