Two‐dimensional Imaging ofPhotofragments

Thoman, John W.; Chandler, David W.; Parker, David H.; Janssen, Maurice H. M.

doi:10.1155/lc.9.27

Cited by 52 publications

(15 citation statements)

References 8 publications

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“…The experimental apparatus and procedures for data collection and analysis have been described previously, − and the specific methods used for these experiments are nearly identical to those used for the N 2 images . Briefly, a molecular beam of neat N 2 O is expanded into a vacuum chamber and through a small collimating hole in the repeller plate of an ion optics setup.…”

Section: Methodsmentioning

confidence: 99%

Speed-Dependent Alignment and Angular Distributions of O(¹D₂)from the Ultraviolet Photodissociation of N₂O

Neyer¹,

Heck²,

Chandler³

et al. 1999

J. Phys. Chem. A

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Photofragment ion imaging has been used to study the O(1D2) atoms produced in the ultraviolet (∼200 nm) photodissociation of nitrous oxide (N2O) in a molecular beam. The images of O(1D2) reveal a speed-dependent angular distribution resulting from both variation in the spatial anisotropy of the recoil and alignment of the electronic angular momentum of the O(1D2) fragment. The orbital alignment effects are revealed by a change in the images when different transitions of the O atom are employed in the resonance enhanced multiphoton ionization (REMPI) process. By correlating the O atom anisotropies with previously measured values for the complementary N2 fragments and comparing images collected on two different REMPI transitions, we calculate the relative branching ratios and anisotropies for the three different |m| values (defined along the product recoil axis) of the electronic angular momentum of the O(1D2) fragment. While m = 0 fragments have the highest probability for most O atom speeds, there is a significant change in the alignment and angular distributions for the slower O atoms. We use a simplified dynamical model supported by previous theoretical structure calculations to explain the measured trends and to estimate the relative branching in the excitation to two N2O electronic states.

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Section: Methodsmentioning

confidence: 99%

Speed-Dependent Alignment and Angular Distributions of O(¹D₂)from the Ultraviolet Photodissociation of N₂O

Neyer¹,

Heck²,

Chandler³

et al. 1999

J. Phys. Chem. A

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“…Many of these were reviewed in 1995. 21 The first applications were to further study the dissociation of methyl iodide and its deuterated derivative [22][23][24][25] as well as H 2 S, 22 but further work was performed on methyl bromide, 26 methane, 27 acetylene, 28 and van der Waals molecules. 29 At the same time, product imaging was used for the first time to study bimolecular reactions, for example, H + HI 30 and H + D 2 , 31 and to analyze crossed-beam studies of an energy transfer process, Ar + NO(v = 0, J = 0) → Ar + NO(v = 0, J).…”

Section: Product Imagingmentioning

confidence: 99%

Perspective: Advanced particle imaging

Chandler

Houston

Parker

2017

The Journal of Chemical Physics

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Finite slice analysis (FINA)-A general reconstruction method for velocity mapped and time-sliced ion imaging The Journal of Chemical Physics 147, 013913 (2017) 1445-1447 (1987)], demonstrating the capability of collecting an image of the photofragments from a unimolecular dissociation event and analyzing that image to obtain the three-dimensional velocity distribution of the fragments, the efficacy and breadth of application of the ion imaging technique have continued to improve and grow. With the addition of velocity mapping, ion/electron centroiding, and slice imaging techniques, the versatility and velocity resolution have been unmatched. Recent improvements in molecular beam, laser, sensor, and computer technology are allowing even more advanced particle imaging experiments, and eventually we can expect multi-mass imaging with co-variance and full coincidence capability on a single shot basis with repetition rates in the kilohertz range. This progress should further enable "complete" experiments-the holy grail of molecular dynamics-where all quantum numbers of reactants and products of a bimolecular scattering event are fully determined and even under our control. Published by AIP Publishing.

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“…The most popular means of analyzing imaging data require the detection of the entire product velocity distribution, but products typically move so quickly and laser bandwidths are usually so narrow that only a Doppler-selected subset of the products are ionized at a single wavelength. To overcome this problem, researchers typically scan the probe laser over the Doppler lineshape, attempting to produce a top-hat frequency profile [21]. The Doppler-free method, in which all molecules are ionized at a single laser wavelength, presents an alternative approach.…”

Section: Application To Ion Imagingmentioning

confidence: 99%

Doppler-free multi-photon ionization: a proposal for enhancing ion images

Pomerantz

Zare

2003

Chemical Physics Letters

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We report on the use of Doppler-free 2 þ 1 resonance enhanced multi-photon ionization (REMPI) to probe H atoms resulting from HBr photolysis at 243 nm. The Doppler-free technique allows almost all H atoms to be ionized at a single probe wavelength, regardless of their lab-frame velocities. This technique yields a significant enhancement in ionization efficiency of the product while leaving the background ionization essentially unaffected. We point out the utility of this technique for the ion imaging of reaction products.

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Two‐dimensional Imaging ofPhotofragments

Cited by 52 publications

References 8 publications

Speed-Dependent Alignment and Angular Distributions of O(¹D₂)from the Ultraviolet Photodissociation of N₂O

Speed-Dependent Alignment and Angular Distributions of O(¹D₂)from the Ultraviolet Photodissociation of N₂O

Perspective: Advanced particle imaging

Doppler-free multi-photon ionization: a proposal for enhancing ion images

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Two‐dimensional Imaging ofPhotofragments

Cited by 52 publications

References 8 publications

Speed-Dependent Alignment and Angular Distributions of O(1D2)from the Ultraviolet Photodissociation of N2O

Speed-Dependent Alignment and Angular Distributions of O(1D2)from the Ultraviolet Photodissociation of N2O

Perspective: Advanced particle imaging

Doppler-free multi-photon ionization: a proposal for enhancing ion images

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Product

Resources

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Speed-Dependent Alignment and Angular Distributions of O(¹D₂)from the Ultraviolet Photodissociation of N₂O

Speed-Dependent Alignment and Angular Distributions of O(¹D₂)from the Ultraviolet Photodissociation of N₂O