Wiley-Mclaren type

Figure Bl.7.17. (a) Schematic diagram of a single acceleration zone time-of-flight mass spectrometer, (b) Schematic diagram showing the time focusing of ions with different initial velocities (and hence initial kinetic energies) onto the detector by the use of a reflecting ion mirror, (c) Wiley-McLaren type two stage acceleration zone time-of-flight mass spectrometer.

The femtosecond laser pulses shaped by the AOPDF are amplified by the CPA up to 0.5mJ/pulse. Ethanol vapor is continuously flow into the vacuum chamber through a micro-syringe (70 pm) with stagnation pressure of 7 Torr at room temperature. The laser pulses are focused on a skimmed molecular beam of the ethanol vapor with an achromatic lens (/ = 145 mm). The focal spot size of the laser beam is 20 pm(j>. The peak intensity of the transform-limited laser pulse is calculated to 4 x 1015 W/cm2. The fragment ions are mass-separated with Wiley-McLaren type time-of-flight (TOF) mass spectrometer, and are detected with a microchannel plate (MCP) detector. 

The relationship between the initial velocity of the incoming neutral species and the TOF for the ionized species to reach the MCP detector is well known for the set-up shown in Figure 9.1, which is known as the Wiley-McLaren-type TOF mass spectrometer [21]. The right and left ordinates of the lower panel of Figure 9.6 show the relationship between the initial velocity and the flight time under our experimental set-up. Detailed discussion on the relation will be made elsewhere [18]. Instead, we will focus on... 

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