MELEXIR: maximum entropy Legendre expanded image reconstruction. A fast and efficient method for the analysis of velocity map imaging or photoelectron imaging data

Dick, Bernhard

doi:10.1039/c9cp03353j

Cited by 25 publications

(15 citation statements)

References 74 publications

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“…The isotope 35 Cl was selected in the present experiment. The maximum entropy Legendre expanded image reconstruction (MELEXIR) method was used to reconstruct the photoelectron distribution from the projected images …”

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confidence: 99%

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Structural Versatility and Energy Difference of Salt–Water Complex NaCl(H₂O) Encoded in Cryogenic Photoelectron Spectroscopy

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2022

J. Phys. Chem. Lett.

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A weakly bound complex usually has multiple structural isomers with small energy differences. The sophisticated ab initio calculations are the main workhorse for providing theoretical results of different isomers. In contrast, the experimental determination of the energy difference is very rare. We report the energy-difference measurement of a model complex: salt–water complex NaCl(H2O). We measured the energy difference among the structural isomers of the negatively charged NaCl(H2O) complex and the neutral counterpart using cryogenic photoelectron spectroscopy. The temperature-dependent photoelectron spectra (15–300 K) revealed that the negatively charged NaCl(H2O) and the neutral counterpart both have three isomers. The two higher-lying isomers are 186(22) and 481(48) cm–1, respectively, above the most stable isomer for the negatively charged and 123(10) and 1821(24) cm–1 for the neutral. These results provide a benchmark for the development of theoretic methods of weakly bound complexes. The experimental technique demonstrated here can be employed to investigate other weakly bound complexes with multiple isomers.

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confidence: 99%

“…The maximum entropy Legendre expanded image reconstruction (MELEXIR) method was used to reconstruct the photoelectron distribution from the projected images. 48 Figure 1 shows the photoelectron energy spectrum of NaCl(H 2 O) − in comparison with that of NaCl − . The well resolved peaks in Figure 1a are the vibrational progression of Na−Cl.…”

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confidence: 99%

Structural Versatility and Energy Difference of Salt–Water Complex NaCl(H₂O) Encoded in Cryogenic Photoelectron Spectroscopy

Ning

2022

J. Phys. Chem. Lett.

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“…An Abel inversion of the images is performed using the MELEXIR , algorithm from the MaxEntAbel package. The essential requirement to perform the Abel inversion using the Melexir algorithm is to have rotationally symmetric images.…”

Section: Methodsmentioning

confidence: 99%

Study of He/Ne+Ar, Kr, N₂, H₂, D₂ Chemi-Ionization Reactions by Electron Velocity-Map Imaging

et al. 2021

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The chemi-ionization of Ar, Kr, N2, H2, and D2 by Ne(3P2) and of Ar, Kr, and N2 by He(3S1) was studied by electron velocity map imaging (e-VMI) in a crossed molecular beam experiment. A curved magnetic hexapole was used to state-select the metastable species. Collision energies of 60 meV were obtained by individually controlling the beam velocities of both reactants. The chemi-ionization of atoms and molecules can proceed along different channels, among them Penning ionization and associative ionization. The evolution of the reaction is influenced by the internal redistribution of energy, which happens at the first reaction step that involves the emission of an electron. We designed and built an e-VMI spectrometer in order to investigate the electron kinetic energy distribution, which is related to the internal state distribution of the ionic reaction products. The analysis of the electron kinetic energy distributions allows an estimation of the ratio between the two-reaction channel Penning and associative ionization. In the molecular cases the vibrational or electronic excitation enhanced the conversion of internal energy into the translational energy of the forming ions, thus influencing the reaction outcome.

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“…MEVELER provides notably better than MEVIR for ion images with low intensity. Later, in 2019, Dick implemented maximum entropy Legendre expanded image reconstruction (MELEXIR) [19], a similar technique like MEVELER but with several advantages. It uses low CPU memory, is faster, and can analyze the data containing higher-order and odd-order Legendre polynomials.…”

Section: Introductionmentioning

confidence: 99%

Effect of slicing in velocity map imaging for the study of dissociation dynamics

Kundu¹,

Biswas²,

Vikrant³

et al. 2021

Preprint

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Inelastic collision dynamics between isolated gas-phase carbon monoxide molecules and low energetic electrons (< 50 eV) has been studied using state-of-the-art velocity map imaging apparatus and reported previously [1,2]. These were based on data analysis using the time-gated parallel slicing technique, which has recently revealed the drawback of lower momentum ion exaggeration mainly due to the inclusion of whole Newton sphere's of diameter ≤ parallel slicing time window. To overcome this drawback, we report implementing a wedge slicing technique so that every momentum sphere contributes equally to the statistics. We also present a comparative study between these two techniques by reanalyzing the data using the time-gated parallel slicing technique. Unlike parallel slicing, the wedge slicing technique better represents the dissociation dynamics, particularly for the ions with low kinetic energy.

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MELEXIR: maximum entropy Legendre expanded image reconstruction. A fast and efficient method for the analysis of velocity map imaging or photoelectron imaging data

Abstract: The MELEXIR program obtains a Legendre expansion of the 3D velocity distribution from 2D images of ions or photoelectrons. The maximum entropy algorithm avoids inverse Abel transforms, is fast and applicable to low-intensity images.

Cited by 25 publications

References 74 publications

Structural Versatility and Energy Difference of Salt–Water Complex NaCl(H₂O) Encoded in Cryogenic Photoelectron Spectroscopy

Structural Versatility and Energy Difference of Salt–Water Complex NaCl(H₂O) Encoded in Cryogenic Photoelectron Spectroscopy

Study of He/Ne+Ar, Kr, N₂, H₂, D₂ Chemi-Ionization Reactions by Electron Velocity-Map Imaging

Effect of slicing in velocity map imaging for the study of dissociation dynamics

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MELEXIR: maximum entropy Legendre expanded image reconstruction. A fast and efficient method for the analysis of velocity map imaging or photoelectron imaging data

Abstract: The MELEXIR program obtains a Legendre expansion of the 3D velocity distribution from 2D images of ions or photoelectrons. The maximum entropy algorithm avoids inverse Abel transforms, is fast and applicable to low-intensity images.

Cited by 25 publications

References 74 publications

Structural Versatility and Energy Difference of Salt–Water Complex NaCl(H2O) Encoded in Cryogenic Photoelectron Spectroscopy

Structural Versatility and Energy Difference of Salt–Water Complex NaCl(H2O) Encoded in Cryogenic Photoelectron Spectroscopy

Study of He*/Ne*+Ar, Kr, N2, H2, D2 Chemi-Ionization Reactions by Electron Velocity-Map Imaging

Effect of slicing in velocity map imaging for the study of dissociation dynamics

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Structural Versatility and Energy Difference of Salt–Water Complex NaCl(H₂O) Encoded in Cryogenic Photoelectron Spectroscopy

Structural Versatility and Energy Difference of Salt–Water Complex NaCl(H₂O) Encoded in Cryogenic Photoelectron Spectroscopy

Study of He/Ne+Ar, Kr, N₂, H₂, D₂ Chemi-Ionization Reactions by Electron Velocity-Map Imaging