Slice imaging: A new approach to ion imaging and velocity mapping

Gebhardt, Christoph; Rakitzis, T. Peter; Samartzis, Peter C.; Ladopoulos, Vlassis; Kitsopoulos, Theofanis N.

doi:10.1063/1.1403010

Cited by 280 publications

(214 citation statements)

References 13 publications

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“…In contrast with the slice imaging technique, the 3D distribution is directly obtained from the sliced images, 49 without the artificial noise introduced by the transform methods and an enhanced energy resolution in relation to that achieved with the velocity mapping technique. We used delayed pulsed extraction slicing 50 in the single field configuration developed by Kitsopoulos and Papadakis and described in detail in Ref. 51.…”

Section: Methodsmentioning

confidence: 99%

The photodissociation of CH3I in the red edge of the A-band: Comparison between slice imaging experiments and multisurface wave packet calculations

Rubio-Lago

Garcı́a-Vela

Arregui

et al. 2009

The Journal of Chemical Physics

110

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The photodissociation of methyl iodide at different wavelengths in the red edge of the A-band ͑286-333 nm͒ has been studied using a combination of slice imaging and resonance enhanced multiphoton ionization detection of the methyl fragment in the vibrational ground state ͑ =0͒. The kinetic energy distributions ͑KED͒ of the produced CH 3 ͑ =0͒ fragments show a vibrational structure, both in the I͑ 2 P 3/2 ͒ and I ‫ء‬ ͑ 2 P 1/2 ͒ channels, due to the contribution to the overall process of initial vibrational excitation in the 3 ͑C-I͒ mode of the parent CH 3 I. The structures observed in the KEDs shift toward upper vibrational excited levels of CH 3 I when the photolysis wavelength is increased. The I͑ 2 P 3/2 ͒ / I ‫ء‬ ͑ 2 P 1/2 ͒ branching ratios, photofragment anisotropies, and the contribution of vibrational excitation of the parent CH 3 I are explained in terms of the contribution of the three excited surfaces involved in the photodissociation process, 3 Q 0 , 1 Q 1 , and 3 Q 1 , as well as the probability of nonadiabatic curve crossing 1 Q 1 ← 3 Q 0 . The experimental results are compared with multisurface wave packet calculations carried out using the available ab initio potential energy surfaces, transition moments, and nonadiabatic couplings, employing a reduced dimensionality ͑pseudotriatomic͒ model. A general qualitative good agreement has been found between theory and experiment, the most important discrepancies being in the I͑ 2 P 3/2 ͒ / ͓I͑ 2 P 3/2 ͒ +I ‫ء‬ ͑ 2 P 1/2 ͔͒ branching ratios. Inaccuracies of the available potential energy surfaces are the main reason for the discrepancies.

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Section: Methodsmentioning

confidence: 99%

The photodissociation of CH3I in the red edge of the A-band: Comparison between slice imaging experiments and multisurface wave packet calculations

Rubio-Lago

Garcı́a-Vela

Arregui

et al. 2009

The Journal of Chemical Physics

110

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“…2 A special ion lens geometry was used to reduce the spatial blurring due to the extended size of the ion source. More recently, Kitsopoulos and co-workers, 3 Suits and co-workers, 4 and Liu and co-workers 5 demonstrated how a slice of the threedimensional ion cloud can be obtained by spreading the ion cloud in time. This latter method, called slice imaging, has the advantage that there are no restrictions with respect to cylindrical symmetry for analyzing the imaging data.…”

Section: Introductionmentioning

confidence: 99%

Slice imaging of photodissociation of spatially oriented molecules

Lipciuc

Brom

Dinu

et al. 2005

Review of Scientific Instruments

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An electrostatic ion lens to spatially orient parent molecules and to image the angular distribution of photofragments is presented. Photodissociation of laboratory-oriented molecules makes it possible to study the dynamics of the dissociation process in more detail compared to photodissociation of nonoriented molecules. Using the velocity map imaging technique in combination with the slice imaging technique, the spatial recoil distribution of the photofragments can be measured with high resolution and without symmetry restrictions. Insertion of orientation electrodes between the repeller and the extractor of a velocity mapping electrostatic lens severely distorts the ion trajectories. The position where the ions are focused by the lens, the focal length, can be very different in the directions parallel and perpendicular to the inserted orientation electrodes. The focal length depends on the exact dimensions and positions of the electrodes of the ion lens. As this dependence is different in both directions, this dependence can be used to correct for the distorted ion trajectories. We discuss the design of an electrostatic ion lens, which is able to orient parent molecules and map the velocity of the photofragments. We report sliced images of photofragments from photolysis of spatially oriented CD 3 I molecules to demonstrate the experimental combination of molecular orientation and velocity map slice imaging with good resolution.

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“…This loss arises from the reduction in dimensionality in the projection of the three-dimensional ͑3D͒ expanding Newton sphere onto a two-dimensional ͑2D͒ detector. In order to reconstruct the 3D distribution, either a mathematical reconstruction or the use of elegant slice-imaging techniques [5][6][7][8] is required. In the latter, only the center slice through the expanding 3D distribution is detected, however, such experiments are generally more involved and very challenging for light particles such as photoelectrons.…”

Section: Introductionmentioning

confidence: 99%

Toward real-time charged-particle image reconstruction using polar onion-peeling

Roberts

Nixon

Lecointre

et al. 2009

Review of Scientific Instruments

244

236

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Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. A method to reconstruct full three-dimensional photofragment distributions from their two-dimensional ͑2D͒ projection onto a detection plane is presented, for processes in which the expanding Newton sphere has cylindrical symmetry around an axis parallel to the projection plane. The method is based on: ͑1͒ onion-peeling in polar coordinates ͓Zhao et al., Rev. Sci. Instrum. 73, 3044 ͑2002͔͒ in which the contribution to the 2D projection from events outside the plane bisecting the Newton sphere are subtracted in polar coordinates at incrementally decreasing radii; and ͑2͒ ideas borrowed from the basis set expansion ͑pBASEX͒ method in polar coordinates ͓Garcia et al., Rev. Sci. Instrum. 75, 4989 ͑2004͔͒, which we use to generate 2D projections at each incremental radius for the subtraction. Our method is as good as the pBASEX method in terms of accuracy, is devoid of centerline noise common to reconstruction methods employing Cartesian coordinates; and it is computationally cheap allowing images to be reconstructed as they are being acquired in a typical imaging experiment.

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Slice imaging: A new approach to ion imaging and velocity mapping

Cited by 280 publications

References 13 publications

The photodissociation of CH3I in the red edge of the A-band: Comparison between slice imaging experiments and multisurface wave packet calculations

The photodissociation of CH3I in the red edge of the A-band: Comparison between slice imaging experiments and multisurface wave packet calculations

Slice imaging of photodissociation of spatially oriented molecules

Toward real-time charged-particle image reconstruction using polar onion-peeling

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