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 Detector 2 4 : Wien filter 7 : Deflection  11 : Focalisation quadrupole 12 : Deceleration plates 13 : Interaction zone 14 : Laser 15 : Column of constant F 16 : MCP 17 : Phosphor screen 18 : CCD 9 1 11 13 3 ion z0 l0 = 0.045 mm a = 0.35 mm F = 427 Vm-1 j e = 0,926 ± 0,002 cm-1 R Rmax Electron affinity (m-1) e neutral atom hn eA Laser pulse energy (µJ) negative ion Pulsed photodetachment microscopy and the electron affinity of Iodine C. Blondel, C. Delsart, C. Drag and R. J. Peláez Laboratoire Aimé-Cotton, Centre national de la recherche scientifique, bâtiment 505, université Paris-sud, F-91405 Orsay cedex, France Photodetachment microscopy Pulsed laser Main properties Tunable single longitudinal mode. Dual polarization stabilized He-Ne Sigmameter Q-CW Classical parameters Highest height Long & short time stabilization Pumped QCW 20 Hz, 515 nm Ti:Sa QCW, 150 µs Lambdameter WSU uncertain. +/- 0.041 m-1 Nanosecond pulse Maximum radius L. Cabaret, Appl. Phys.B 94 (2009) 71 Energy ≈ 400mJ Quantum parameters : Frequency-doubled Nd:YAG 25 mJ @ 532 nm Pulsed Ti:Sa ~ 10 mJ @ 810 nm BBO Uncertainty ≈0.8 m-1 ~ 1 mJ @ 405 nm 15 ns Wavelength scale L. Cabaret and C. Drag, Eur. Phys. J. Appl. Phys.37 (2006) 65 Number of rings Interfrange distance Radial current density 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 : C. Delsart et al., Phys. Rev . Lett.89 (2002) 183002 New result : electron affinity of 127I 2P3/2 F2 = 4 14.097 m-1 F2 = 3 Electron Count 6.5575 m-1 F2 = 2 2.46 m-1 F2 = 1 Experimental set-up I [F2]=2 F2 +1 eA = 2 467 287(3) m-1 Barycenter Accumulation 1S0 F1 = 5/2 Radius (mm) Ponderomotive effect : electron oscillations in electromagnetic waves. 18 17 16 Ponderomotive effects have been negligible, for two reasons: i) Blue wavelength (~ 405 nm) ii) Low energy ≈ 400µJ Doppler Effect 15 Electron Affinity (eV) 14 Electron Affinity (eV) eA(127I) = 2 467 286.7 (28) m-1 = 3.059 0453 (36) eV R. J. Peláez et al.J. Phys. B. 42 (2009) 125001 41st EGAS, Gdansk, 8-11 July 2009