Surface-aligned femtochemistry: Photoinduced reaction dynamics of CH3I and CH3Br on MgO(100)

Vaida, Mihai E.; Bernhardt, Thorsten M.

doi:10.1039/c2fd20104f

Cited by 13 publications

(15 citation statements)

References 56 publications

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“…In 2012, the group concentrated again on CH 3 I and CH 3 Br adsorbed to a MgO surface (Vaida & Bernhardt, 2012). This time, also one-color multiphoton ionization was investigated.…”

Section: Photodissociationmentioning

confidence: 99%

Photoionization and photofragmentation in mass spectrometry with visible and UV lasers

Gunzer

Krüger

Grotemeyer

2018

Mass Spectrometry Reviews

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Ever since the introduction of laser technology to the field of mass spectrometry, several disciplines evolved providing solutions to challenging scientific and analytical tasks in research and industry. Among these are techniques involving multiphoton ionization such as Resonance‐Enhanced Multiphoton Ionization (REMPI, R2PI) and Mass‐Analyzed Threshold Ionization (MATI) spectroscopy, a variant of Zero Kinetic Energy (ZEKE) spectroscopy, that possess the ability to selectively ionize certain preselected compounds out of complex mixtures, for example, environmental matrices, with a high level of efficiency. Another key feature of multiphoton ionization techniques is the ability to control the degree of fragmentation, whereas soft ionization is most highly appreciated in most applications. In cases where rich fragmentation patterns are desired for diagnostic purposes, Photodissociation mass spectrometry (PD‐MS) is applied successfully. PD‐MS allows for the cleavage of selected chemical bonds. With the introduction of chromophoric labels in PD‐MS, it became possible to target certain molecules or groups within a molecule. In this review article, an overview of the basic principles and experimental requirements of REMPI and MATI spectroscopy and PD mass spectrometry are given. By means of selected examples, the latest developments and application possibilities in this field over the past decade with special focus on the German research landscape are pointed out. © 2018 Wiley Periodicals, Inc. Mass Spec Rev 38: 202–217, 2019.

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“…In 2012, the group concentrated again on CH 3 I and CH 3 Br adsorbed to a MgO surface (Vaida & Bernhardt, 2012). This time, also one-color multiphoton ionization was investigated.…”

Section: Photodissociationmentioning

confidence: 99%

Photoionization and photofragmentation in mass spectrometry with visible and UV lasers

Gunzer

Krüger

Grotemeyer

2018

Mass Spectrometry Reviews

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“…4 would be absorption of two photons of 266 nm, followed by XUV ionization. Recent photodissociation investigations of the CH 3 Br molecule adsorbed at low temperature on insulating surfaces show that the molecular photodissociation can be produced by means of two photon excitation at 266 nm via the 4E state [15,16]. However, the electronic structure and the dissociation dynamics of the adsorbed CH 3 Br molecule might be altered by the presence of the surface.…”

Section: Pump Pulse Excitationmentioning

confidence: 99%

“…The only time-resolved experiment has been performed on CH 3 Br molecules physisorbed on insulating ultrathin magnesia films [15,16]. The CH 3 Br molecules adsorbed on the magnesia surface were found to dissociate in about 150 fs after a two-photon excitation at a central wavelength of 266 nm.…”

Section: Introductionmentioning

confidence: 99%

“…The CH 3 Br molecules adsorbed on the magnesia surface were found to dissociate in about 150 fs after a two-photon excitation at a central wavelength of 266 nm. However, the dissociation time of the CH 3 Br molecule adsorbed on the surface is influenced by the molecular adsorption geometry and the changes in electronic states due to the interaction between the molecule and the surface [16][17][18] and the result does not necessarily reveal the dissociation time of the free molecule.…”

Section: Introductionmentioning

confidence: 99%

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Tracing dissociation dynamics of CH3Br in the 3Q0 state with femtosecond extreme ultraviolet ionization

Vaida¹,

Leone²

2014

Chemical Physics

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The ultrafast photodissociation dynamics of gas phase CH 3 Br molecules in the red wing of the A-band, i.e. the first molecular adsorption continuum, is investigated by pump-probe spectroscopy. The experiment employs femtosecond laser pulses at 266 nm in the ultraviolet to dissociate the molecule and high order harmonic extreme ultraviolet pulses in conjunction with time-of-flight mass spectrometry to ionize and detect the fragments. A dissociation time of 116 ± 25 fs is obtained from the pump-probe risetime of the Br + ion signal, which originates from formation of either or both Br( 2 P 3/2 ) or Br ⁄ ( 2 P 1/2 ). The timescale is in a good agreement with the previously calculated A-band dissociation time of CH 3 Br using the anisotropy parameter b deduced from angular photodissociation experiments. Based on classical molecular dynamics simulations and previous spectroscopic information, the most likely pathway is dissociation of the CH 3 Br molecule via the 3 Q 0 state of the A-band, which correlates with the formation of the spin-orbit excited bromine fragment.

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“…On the bare magnesia thin film, the transient methyl signal starts with an initial delay of 150 ±50 fs and exhibits a single exponential rise with a time constant of 320 ±60 fs, which are in a perfect agreement with the previous CH3Br photodissociation measurements on MgO thin films. [43][44][45][46] The initial coherent delay of 150 ±50 fs reflects the minimal time needed for the liberation of the methyl fragments from the molecular force field and from the force field of the magnesia surface. This time is longer than the A-band dissociation time of CH3Br in the gas phase, i.e.…”

mentioning

confidence: 99%

Non-metal to metal transition of magnesia supported Au clusters affects the ultrafast dissociation dynamics of adsorbed CH3Br molecules

Vaida

Rawal

Bernhardt

et al. 2022

Preprint

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The detection of intermediate species and the correlation of their ultrafast dynamics with the morphology and electronic structure of a surface is crucial to fully understand and control heterogeneous photoinduced and photocatalytic reactions. In this work, the ultrafast photodissociation dynamics of CH3Br molecules adsorbed on variable size Au clusters on MgO/Mo(100) is investigated by monitoring the CH3+ transient evolution using a pump-probe technique in conjunction with surface mass spectrometry. Furthermore, extreme-ultraviolet photoemission spectroscopy in combination with theoretical calculations are employed to study the electronic structure of the Au cluster on MgO/Mo(100). Changes in the ultrafast dynamics of CH3+ fragment are correlated with the electronic structure of Au as it evolves from monomers to small nonmetallic clusters to larger nanoparticles with a metallic character. This work provides a new avenue to a detailed understanding of how surface photoinduced chemical reactions are influenced by the composition and electronic structure of the surface.

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Surface-aligned femtochemistry: Photoinduced reaction dynamics of CH3I and CH3Br on MgO(100)

Cited by 13 publications

References 56 publications

Photoionization and photofragmentation in mass spectrometry with visible and UV lasers

Photoionization and photofragmentation in mass spectrometry with visible and UV lasers

Tracing dissociation dynamics of CH3Br in the 3Q0 state with femtosecond extreme ultraviolet ionization

Non-metal to metal transition of magnesia supported Au clusters affects the ultrafast dissociation dynamics of adsorbed CH3Br molecules

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