Electron pulse length

Figure 3 shows G(Fe3+) as a function of dose-rate for electron pulse lengths of 1.1 fxsec. For 02-saturated solutions there is no dose-rate dependence up to 100 rad/pulse. For air-free solution there is no dose-rate dependence up to 500 rad/pulse. 

A series of consecutive time bins covers a length of time of a few milliseconds, with each bin representing a time of only a fraction of a nanosecond. When an ion arrives at the microchannel array detector, one time bin notes the resulting electronic pulse. 

Figure 11 The components of the timing jitter of the laser synchronized subpicosecond pulse radiolysis, crj is the length of the electron pulse (rms), c,- is the length of the probe light (rms), and ctj is the timing fluctuation (rms).

When the optical length of the sample is much shorter than the other factors such as the length of the electron pulse, the response function takes on a Gaussian shape. As the optical length increases, the shape of the response function becomes trapezoidal. Furthermore, a thick sample causes the prolongation of the electron pulse by electron scattering, which leads to the degradation of time resolution. Therefore the experiment to observe ultrafast phenomena requires the use of a thin sample. 

Schematic diagrams for radio-frequency (r.f.) electronics are shown in Fig. 5.2. The circuit in Fig. 5.2(a) is a simple heterodyne circuit. The pulse length is defined by the switch SI. The speed of this switch determines the minimum pulse length, and hence the minimum lens focal length, and hence the highest frequency of the microscope thus the limit to the resolution is ultimately determined by the highest useful speed of this switch. S2 is the single-pole-double-throw (s.p.d.t.) switch, and Al the low-noise preamplifier. The mixer is a device that takes two inputs, the radio-frequency signal and the...

The switching time for the three-way valve is At = 20 ms and the pulse length is adjustable by a commercial electronic pulse generator. The pulse length can thus be varied from 50 ms to 10 s. A sequence of pulses can also be delivered with... 

---