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Detector

D. F. 7. C. 8. U. 6. 1 : Source and simple lens doublet (“Einzellens") 2,5,9,10 : Deflection plates 3,6,8 : Simple lenses. 10. 4. 5. 12. 2. 4 : Wien velocity filter 7 : Deflection quadrupole 11 : Focalisation quadrupole 12 : Deceleration plates 13 : Interaction zone.

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Detector

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  1. D F 7 C 8 U 6 1 : Source and simple lens doublet (“Einzellens") 2,5,9,10 : Deflection plates 3,6,8 : Simple lenses 10 4 5 12 2 4 : Wien velocity filter 7 : Deflection quadrupole 11 : Focalisation quadrupole 12 : Deceleration plates 13 : Interaction zone 14 : Pulsed Ti:Sa laser 15 : Column of constant F 16 : MCP 17 : Phosphor screen 18 : CCD 9 1 11 13 3 j F = 427 Vm-1 Rmax R Photocurrent (arbitrary unit) OD = 0 Radius (arbitrary unit) Photocurrent (arbitrary unit) OD = 0.4 Radius (arbitrary unit) Photocurrent (arbitrary unit) e neutral atom OD = 1 Radius (arbitrary unit) hn eA Photoelectron energy as a function of the laser pulse energy negative ion Elaser (mJ) PULSED PHOTODETACHMENT MICROSCOPY OF ATOMIC AND MOLECULAR ANIONS Christophe Blondel, Christian Delsart, Cyril Drag & Ramón J. Peláez Laboratoire Aimé-Cotton, Centre national de la recherche scientifique, bâtiment 505, université Paris-sud, F-91405 Orsay cedex, France Photodetachment microscopy Single-mode pulsed laser Main properties a Dual polarization stabilized He-Ne Single longitudinal mode Sigmameter Classical parameters ion WSU lambdameter uncertainty: +/-0.041 m-1 Tunable (250 m-1) Highest height Freq. doubled Q-CW Yb:YAG 515 nm - 20 Hz quasi-CW Ti:Sa150 µs Short & long term stabilized(+/- 20 MHz for 100 min) Maximum radius L. Cabaret, Appl. Phys.B 94 (2009) 71 z0 Quantum parameters : Frequency-doubled Nd:YAG 25 mJ @ 532 nm Pulsed Ti:Sa ~ 10 mJ @ 848 nm Pulse duration ≈ 25 ns Wavelength scale Energy ≈ 3- 10 mJ L. Cabaret and C. Drag, Eur. Phys. J. Appl. Phys.37 (2006) 65 Detector Number of rings Interfringe interval Radial current density l0 = 0.045mm a = 0.35mm e = 0.926 ± 0.002 cm-1 Principle:Y.N. Demkov et al., JETP Lett. 34 (1981) 403 Photodetachment microscopy:C. Blondel et al., Phys. Rev . Lett. 77 (1996) 3755 Photoionization microscopy:C. Nicole et al., Phys. Rev . Lett.88 (2002) 133001 Molecular photodetachment microscopy :F. Goldfarb et al., J. Chem. Phys.122 (2005) 014308 Photodetachment microscopy in a magnetic field :W. Chaibi et al., Eur., Phys. J. D 58 (2010) 29 Ponderomotive effects observed in O- Presence of an EM field reduces the “free” electron kinetic energy by Up=q2E2/4mw2 Highlight dans Eur. Phys. J. D Experimental set-up Barycenter Accumulation 18 17 16 Photodetachment images obtained on O- with attenuation by an optical density OD between 1 and 0. 15 The number of interference rings decreases when the optical density decreases, i.e. when the laser peak intensity increases. At the peak intensity, the energy shift revealed in this way would be -0.27 cm-1/mJ, but the observed effect appears attenuated by the three-dimensional integration on the whole interaction volume and the pulse duration. 14 SPECMO-SOLEIL 22-23 November 2010

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