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Location | | Contact |
ETH Zurich HCI G 228 Wolfgang-Pauli-Strasse 10 8093 Zürich | | Samuel Walt Phone: 0041 44 633 49 79 Email: .swf(aly+t@n,phc5ysk*.cj)hew2m.d6etf3hzw,.cg+ho
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Setup / Configuration - Angularly-resolved momentum distributions for electrons and ions
- Kinetic energies from 0-200 eV can be detected
- 8 cm diameter MCP detector
- Time-of-flight spectrometer
- 1 kHz pulsed valve
- fast electronics for switching MCP gain on/off in <100 ns
- Combinable with attosecond pump-probe setup
| | Literature - D. W. Chandler and P. L. Houston, The Journal of Chemical Physics 87, 1445 (1987).
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Figure 1 shows a cut through the velocity- map imaging system (VMIS). The lower half part consist of an electrostatic lens system and a micro- channel plate detector. The upper part includes the pulsed valve and the skimmer. Each side is pumped by a turbo- molecular pump. A simplified drawing is shown in figure 2.
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Fig. 2. The molecules are ionized with an intense femtosecond near-infrared laser pulse in the center between the repeller and extractor plates. A static electric field focuses the photoelectrons on the MCP detector (Fig. 2a). In order to increase the cooling efficiency, a skimmer is placed between the pulsed valve and the repeller. For experiments with extreme-ultraviolet attosecond laser pulses, high gas densities in the interaction region are required. To this end, the skimmer is removed and the valve is moved very close to the repeller (Fig. 2b). Our VMIS thus offers a continuously tunable target density combined with a controlled degree of molecular cooling in the supersonic expansion. |
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