Position sensitive anodes for MCP read-out using induced charge measurement

Jagutzki, O.; Lapington, J. S.; Worth, Liam B. C.; Spillman, U; Mergel, V.; Schmidt‐Böcking, H.

doi:10.1016/s0168-9002(01)01843-5

Cited by 114 publications

(74 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In the present experiments we used the wellestablished COLTRIMS technique to measure both the neutral projectile H and the recoiling He + ion in coincidence [40][41][42]. The experiment has been performed at the 2. detector with a delay line anode [43,44] 5 m downstream of the target region. The target was provided by a two-stage supersonic gas jet of helium atoms.…”

Section: Methodsmentioning

confidence: 99%

Transfer excitation reactions in fast proton-helium collisions

et al. 2014

View full text Add to dashboard Cite

Continuing previous work, we have measured the projectile scattering-angle dependency for transfer excitation of fast protons (300-1200 keV/u) colliding with helium (p+He → H + He + * ).Our high-resolution fully differential data are accompanied by calculations, performed in the planewave first Born approximation and the eikonal wave Born approximation. Experimentally, we find a deep minimum in the differential cross section around 0.5 mrad. The comparison with our calculations shows that describing the scattering-angle dependence of transfer excitation in fast collisions requires us to go beyond the first Born approximation and in addition to use the initial state-wave function, which contains some degree of angular correlations. * Electronic address: schoeffler@atom.uni-frankfurt.de

show abstract

Section: Methodsmentioning

confidence: 99%

Transfer excitation reactions in fast proton-helium collisions

et al. 2014

View full text Add to dashboard Cite

show abstract

“…The resulting di-and trications then dissociate into several fragments. All ions and photoelectrons are guided to position and timesensitive multihit detectors with weak electric and magnetic fields [13]. The final positions and flight times in fourfold (or fivefold) coincidence for each event are then used to determine the full vector momentum of each particle.…”

mentioning

confidence: 99%

Imaging Polyatomic Molecules in Three Dimensions Using Molecular Frame Photoelectron Angular Distributions

et al. 2012

View full text Add to dashboard Cite

We demonstrate a method for determining the full three-dimensional molecular-frame photoelectron angular distribution in polyatomic molecules using methane as a prototype. Simultaneous double Auger decay and subsequent dissociation allow measurement of the initial momentum vectors of the ionic fragments and the photoelectron in coincidence, allowing full orientation by observing a three-ion decay pathway, (H þ , H þ , CH þ 2 ). We find the striking result that at low photoelectron energies the molecule is effectively imaged by the focusing of photoelectrons along bond directions. DOI: 10.1103/PhysRevLett.108.233002 PACS numbers: 33.80.Eh, 33.60.+q Imaging molecular structure is a critical challenge in chemical physics recently highlighted by the emergence of techniques that, similar to ultrafast electron diffraction [1] or x-ray diffraction [2], have the potential to be taken to the time domain and thereby ultimately be used to make ''movies'' of chemical reactions on their natural time scale. Of particular interest is the development of such techniques that can be applied to the dynamics of isolated molecules. Here, the full three-dimensional orientation of a polyatomic molecule is measured simultaneously with the three components of the momentum of a photoelectron ejected from it with no underlying assumptions of symmetry or geometry. We present three-dimensional images of a polyatomic molecule measured with this technique, demonstrating an effect predicted [3] for polyatomic molecules with a heavy central atom bonded to hydrogens, namely that low-energy photoelectrons can directly image the molecular potential and bond structure.When a photoelectron is launched by photoabsorption of an inner shell, the outgoing photoelectron wave is then scattered by the aggregate potential of the molecule. The final angular distribution in the body-fixed frame of the molecule is an exquisitely sensitive probe of molecular structure and initial electronic state, which has been recently argued and demonstrated [4,5]. However, observing molecular-frame photoelectron angular distributions (MFPADs) at high resolution requires accurate orientation of the molecule in the gas phase. Three-dimensional laser alignment [6,7] can accomplish such orientation prior to photoionization but is limited to molecules with an asymmetric polarizability. In the case of simple diatomic molecules, orientation can also be accomplished by detecting the photoelectron in coincidence with positively charged fragments that emerge following prompt Auger decay and dissociation [8]. Progress has also been made toward threedimensional MFPAD measurement using coincidence detection and velocity map imaging [9]. Here we present photoelectron imaging of methane molecules, where both the photoelectron momentum and corresponding body frame of the polyatomic molecule are fully determined in all three dimensions.For many molecules, including CH 4 , core ionization opens a strong simultaneous double Auger decay channel that produces a trication that then can disso...

show abstract

“…To optimize the resolution, a three dimensional time and space focusing geometry [18,19] was used for the recoil ion arm of the spectrometer. The ion were detected by a 80 mm diameter micro channel plate (MCP) detector with delay-line anode [20,21]. The time focusing was realized using a field free drift tube [22], while an adjustable electrostatic lens was used to achieve space focusing.…”

Section: Methodsmentioning

confidence: 99%

Two-dimensional electron-momentum distributions for transfer ionization in fast proton-helium collisions

et al. 2013

View full text Add to dashboard Cite

The momentum distribution of the electron in the reaction p+He → H + He 2+ + e is measured for projectile energies E p =300 and 630 keV/u at very small scattering angles of hydrogen. We mainly present two dimensional distributions parallel (k || ) and perpendicular (k ⊥ ) to the projectile beam. Theoretical calculations were carried out within the Plane Wave First Born Approximation (PWFBA), which includes both electron emission mechanisms, shake-off and sequential capture and ionization. It is shown that electron correlations in the target wave function play the most important role in the explanation of experimentally observed backward emission. Second order effects have to be involved to correctly describe the forward emission of the electron. * Electronic address: schoeffler@atom.uni-frankfurt.de 2

show abstract

Position sensitive anodes for MCP read-out using induced charge measurement

Cited by 114 publications

References 9 publications

Transfer excitation reactions in fast proton-helium collisions

Transfer excitation reactions in fast proton-helium collisions

Imaging Polyatomic Molecules in Three Dimensions Using Molecular Frame Photoelectron Angular Distributions

Two-dimensional electron-momentum distributions for transfer ionization in fast proton-helium collisions

Contact Info

Product

Resources

About