Pulse amplitude duration

The CCF is sensitive to variations in all the signal parameters carrier frequencies, phases, pulse forms, durations and amplitudes. Both signal amplitudes A, and J in formula (1) can factor outside the integral sign and do not define its value. Hence we let the CCF as N= MIA or in normalized form N = NIN . ... 

CCF dependences on the -factor of loaded probe vibrators are shown in Fig.4. For s(l) pulses growth of 2 factor increase CCF maximum amplitude and selectivity. In this case the higher the Q, the longer the pulse duration and the more its periods contribute to the processing. F or q(t) pulses rising of g-factor decrease CCF maximum amplitudes and reduce the selectivity. As q(l) pulse consists of a few first periods only its maximum amplitude depends on Q. the higher the Q, the lower the final pulse amplitude, and therefore, CCF amplitude and selectivity. 

For phase encoding of a velocity component, a gradient pulse sequence similar to the sequence in Figure 2.9.4(b) can be used. Two gradient pulses of duration t and of the same magnitude of the amplitude Gx but with opposite sign are applied. The position dependent term of the phase shift vanishes whereas the velocity dependent term provides a finite phase shift proportional to the velocity component [see Figure 2.9.4(b)] ... 

This contribution will describe the manipulation of spin multiplets as a whole, and the word selective - or soft - will be used for multiplet-selective pulses, in contrast to band-selective, which refers to a broader bandwidth which may affect several spins, and to transition selective when only one line is affected. The discussion will be based on proton spectra, but all aspects are similar for other nuclei. Soft pulses use lower amplitudes and much longer irradiation times than non-selective hard pulses. Typical durations for soft pulses are of the order of 1 to 500 ms with a peak amplitude... 

When the pulse amplitude, AE, tends to zero and the scan rate is held constant (i.e., the pulse duration also tends to zero in order to keep the ratio v = A /t constant), the potential-time perturbation applied in SCV becomes a continuous ramp of potentials and so can be identified with the potential-time perturbation applied in Linear Sweep Voltammetry (LSV,2 see Scheme 5.2). 

For each shaped pulse you must select the pulse width (duration in p,s Brukerpl2,pl3, etc., or Varian selpw), the name of the text file that contains the shape function (Bruker spnaml, spnam2, etc., Varian selshape), the maximum power (B amplitude) at the top of the pulse shape (Bruker spl, sp2, etc., or Varian selpwr), and the offset frequency in hertz... 

Figure 3. Differential pulse voltammogram of a mixture of dibenzothiophene and benzothiophene in acetonitrile. Supporting electrolyte 0.1 M tetraethylammonium perchlorate. Indicator electrode glassy carbon disk, rotated at 1800 rpm. Linear potential ramp, 0.002 volt/s. Pulse amplitude, AE = 0.025 V. Pulse duration, 57 ms. Current sampling time, 17 ms.

In normal pulse voltammetry a base value of potential, 5ase, is chosen, normally where there is no faradaic reaction, and this is applied to the electrode. From this value short pulses of increasing amplitude are applied, the amplitude increment always being equal. The current is measured at the end of each pulse, the duration of which varies normally between 5 and 100 ms the interval between pulses is 2-4 s. Figure 10.9 shows the scheme of operation and response. 

During the "off period" the electrons re-establish equilibrium with the gas. The three operating variables are the pulse duration, pulse frequency and pulse amplitude. The relationship between the number of electrons collected and the collecting time (the pulse width) is shown in figure 13. It is seen that with no methane present electron collection takes nearly 3 psec to complete. However, with 5% or 10% of methane present in the argon all the electrons are collected in less than 1 psec. This reflects the increased diffusion rates of the electrons in argon-methane mixtures. By appropriate adjustment of the pulse characteristics, the current can be made to reflect the relative... 

Multiple-pulse sequences, in which the individual square pulses have different rf amplitudes 6, are experimentally more demanding. Multiple-pulse sequences with delays can be regarded as special cases of this class of sequences. Delays correspond to pulses of duration with vanishing rf amplitude vj = 0. For multiple-pulse sequences with constant rf amplitude F, except for the delays, where the rf amplitude is zero, the average rf power is proportional to... 

Fig. 4.8 shows experimental plots of the number of nuclei Znuc vs. time (pulse duration) at different overvoltages (pulse amplitudes) in the electrodeposition of mercury on platinum [4.37]. The steady state nucleation rate (dZnuc/dt = /= const.) is... 

Figure 3.1. Fourier relationship between an rf pulse of duration Tp and the amplitude distribution A(v) of the frequency components present.

In order to work with mammalian cells, pulse parameters need to be much better controlled, and this is efficiently done with a square wave electroporator [3]. Here, the pulse amplitude and duration may be individually controlled, allowing a much better adaptability to the target cells or tissues as well as to the molecule that is to be transferred. Another important stage of the development has been the availabihty of square wave pulse generators designed and approved for chnical use. 

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