Setup for the Real-Time Charge Reversal NeNePo Experiments

2 Setup for the Real-Time Charge Reversal (NeNePo) Experiments 

As introduced in Chap. 1, a real-time NeNePo experiment on molecules or clusters starts with a photodetachment process followed by a photoionization step, each induced by an ultrashort laser pulse (see Fig.2.25). In Chap.5 the first, fascinating results measured with this technique are presented. The setup for this high-performance, femtosecond NeNePo charge reversal experiment is shown in Fig. 2.26. The special features of the laser system employed are then given, followed by a few fundamental details on generation, storage, and detection of the investigated particles. 

Quadrupole Gas Quadrupole mass filter mass filter 

Ultrashort Laser System. To analyze the time evolution of the neutral trimer s configuration a laser system consisting of a titanium sapphire oscillator (Spectra Physics Tsunami) which is pumped by a 12 W argon ion laser, and a Nd YLF-pumped regenerative amplifier system (Quantronix 4800 titanium sapphire RGA) is employed [175]. 

The amplifier system is composed of three logic subunits, a femtosecond pulse stretcher (Fig. 2.27), the titanium sapphire regenerative amplifier (Fig. 2.28) and a femtosecond pulse compressor (Fig. 2.29). To exploit the storage capability of titanium sapphire the system uses chirped-pulse amplification [264-266]. For this a seed pulse (80 fs, 5nJ) of the titanium sapphire oscillator is stretched to about 500 ps and then amplified. The stretched pulse can be safely amplified because the peak power has been significantly lowered, thereby avoiding any nonlinear effects that could result in damage to the 

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