A velocity map imaging detector with an integrated gas injection system

FOM-Institute for Atomic and Molecular Physics (AMOLF), Kruislaan 407, 1098 SJ Amsterdam, The Netherlands.
The Review of scientific instruments (Impact Factor: 1.61). 04/2009; 80(3):033110. DOI: 10.1063/1.3085799
Source: PubMed


We present the design of a velocity map imaging spectrometer where the target gas is injected from a capillary that is integrated in the repeller plate of the ion optics assembly that drives electrons/ions formed by ionization or dissociation to a two-dimensional detector. The geometry of this design allows the use of gas densities in the interaction region that are two to three orders of magnitude higher than the densities that are used in standard velocity map imaging spectrometers, making the detector suitable for working with weak light sources such as newly developed attosecond pulse sources, or (quasi-)cw sources such as synchrotrons. In a test where monoenergetic photoelectrons were generated by six-photon ionization of Xe (utilizing the second harmonic of a neodymium doped Nd:YAG), the kinetic energy resolution of the spectrometer was found to be DeltaE/E=1.8%. This number was found to be in good agreement with Monte Carlo simulations.

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Available from: Omair Ghafur, Apr 23, 2014
    • "First, velocity map imaging (VMI) [52] [53] [54] is a technique where particles with the same mass and initial velocity are mapped onto the same position on a 2D detector. A VMI can provide electronic and ionic kinetic energies and angular distributions with full 4π-sr collection while achieving energy resolutions on the percent level [55]. Most VMI apparatuses require cylindrical symmetry to transform the detected projection into a slice through the center of the 3D momentum distribution; however, in special implementations , this is not necessarily the case [56] [57] [58] [59]. "
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