Molecular-beam studies of Penning ionization

Siska, P. E.

doi:10.1103/revmodphys.65.337

Cited by 283 publications

(319 citation statements)

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“…In spite of the rather low dissociation rate, this contribution is still comparatively small since at thermal energies the (total) Penning ionization cross section for He*(23S) + Hz collisions is more than an order of magnitude smaller than the corresponding He*(2") + H cross section ( u . H~( E~~~= 50meV)=1.89~ 10-'6cm2, u,(Ek,.=50meV)=2.85x 10-'5cm2 (Bamett 1990, Siska 1993). …”

Section: Data Processingmentioning

confidence: 99%

“…Studies ofcollisional autoionization processes represent an active field of research (Siska 1993, Brunetti and Vecchiocattivi 1993, Klyucharev 1993 Urbain 1993), partly due to their one-electron character, but also because of the availability of suitable excitation lasers and laser-cooling schemes. The theoretical interpretation of the bi-excited alkali systems is, however.…”

Section: Introductionmentioning

confidence: 99%

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Ionization of hydrogen and deuterium atoms in thermal energy collisions with metastable He*(2³S) atoms

Merz

Ruf

Hotop

et al. 1994

J. Phys. B: At. Mol. Opt. Phys.

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Abstract. We report experimental and theoretical results for the basic autoionization processesHe*(2'S)+H,'D(I~),leadingtoPenning(-He+H',:D'te~(@. &)) andassociative ionization (-HeH+/HeD' (vi, J ') +e-(@, E ) ) . The experimental electron energy spectra. measured at thermal collision energies (&%50 meV), show an angulardependent behaviour which is due to the interplay between the orientation of the collision complex at the moment of autoionization-as referred to the relative velocity direction-and a strongly non-isotropic internal angular distribution for electron emission from the excited quasimolecule. The ab inilio work on He*(Z'S)+H/D includes electron angular momentum dependent complex (resonance-to-continuum) coupling elements. revealing substantial contributions of autoionization into the electronic d wave. Comparison between the anglediRerentia1 experimental electron spectra. measured with an energy resolution of 30 meV, and the corresponding theoretical distributions, obtained in the framework of the local complex potential theory, yields good agreement for both isotopes.

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Section: Data Processingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Ionization of hydrogen and deuterium atoms in thermal energy collisions with metastable He*(2³S) atoms

Merz

Ruf

Hotop

et al. 1994

J. Phys. B: At. Mol. Opt. Phys.

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“…This technique, called metastable atom bombardment (MAB) [6], is based on Penning ionization [7]: An electrophilic reaction of a metastable species with an analyte. Eq 1 represents this process:…”

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confidence: 99%

“…However, if the energy difference is large, the reaction shown in eq 2 is favored and extensive fragmentation can result. Table 1 shows the excitation energy and the lifetime of the metastable species of the gases used for MAB ionization [7][8][9]. During the excitation process, each gas generates more than one metastable state.…”

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Temperature-programmed pyrolysis hyphenated with metastable atom bombardment ionization mass spectrometry (TPPy/MAB-MS) for the identification of additives in polymers

Boutin

Lesage

Ostiguy

et al. 2004

J. Am. Soc. Mass Spectrom.

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Thermoanalytical techniques are currently used for the analysis of additives contained in polymers that cannot be easily dissolved, extracted, or hydrolyzed. With these techniques, the polymers are heated to liberate the additives trapped in the polymer matrix. If the polymer is heated slowly, up to its thermal degradation, the technique is called temperature-programmed pyrolysis (TPPy). For TPPy experiments, mass spectrometry is generally used as the detection method. The ionization sources commonly used in mass spectrometry, such as CI and EI, can cause fragmentation during the ionization process. Fragmentation decreases the sensitivity of the molecular ions and increases the risks of interferences with the compounds coming from the matrix. An energy-tunable ionization technique, called metastable atom bombardment (MAB), is proposed for TPPy/MS experiments. With this ionization source, the energy of ionization depends on the metastable gas used. With low-energy metastable gases such as Xe or N 2 , fragmentation is reduced compared to CI, whereas with medium-energy metastable gases such as Ar or Kr, the fragmentation is similar to that observed with CI. TPPy/MAB-MS was performed on an unknown polyurethane-based car paint. The detection of molecular ions and characteristic fragments with MAB(N 2 ) led to the identification of two light stabilizers: Bis (1,2,2,6,6-pentamethyl-4-piperidinyl)sebacate (BPPS) and 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol (PTPP). Using MAB(Ar) to simulate CI, the molecular ion and one of the two characteristic fragments of BPPS were not detected, thus confirming the advantage of using MAB(N 2 ) ionization for TPPy/MS experiments. (J Am Soc Mass Spectrom 2004, 15, 1315-1319

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Quantum Control of Molecular Processes

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Molecular-beam studies of Penning ionization

Cited by 283 publications

References 330 publications

Ionization of hydrogen and deuterium atoms in thermal energy collisions with metastable He*(2³S) atoms

Ionization of hydrogen and deuterium atoms in thermal energy collisions with metastable He*(2³S) atoms

Temperature-programmed pyrolysis hyphenated with metastable atom bombardment ionization mass spectrometry (TPPy/MAB-MS) for the identification of additives in polymers

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Molecular-beam studies of Penning ionization

Cited by 283 publications

References 330 publications

Ionization of hydrogen and deuterium atoms in thermal energy collisions with metastable He*(23S) atoms

Ionization of hydrogen and deuterium atoms in thermal energy collisions with metastable He*(23S) atoms

Temperature-programmed pyrolysis hyphenated with metastable atom bombardment ionization mass spectrometry (TPPy/MAB-MS) for the identification of additives in polymers

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Ionization of hydrogen and deuterium atoms in thermal energy collisions with metastable He*(2³S) atoms

Ionization of hydrogen and deuterium atoms in thermal energy collisions with metastable He*(2³S) atoms