Femtosecond timescale deactivation of electronically excited peroxides at ice surfaces

Shemesh, Dorit; Gerber, R. B.

doi:10.1080/00268976.2012.666279

“…Nonspherical aerosol particles arouse particular interest due to their specific properties. In the form of desert dust, volcanic ash, soot and ice particles they act as catalyzers of photochemical reactions 16,17,21 , cloud condensation nuclei 9 and ice nucleation centers 10 . They also promote alternate pathways of new particle formation 17 .…”

Section: Introductionmentioning

confidence: 99%

Morphology and motion of single optically trapped aerosol particles from digital holography

David

¹

,

Esat

²

,

Thanopulos

³

et al. 2018

Optical Trapping and Optical Micromanipulation XV

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Nonspherical particles play a key role in the atmosphere by affecting processes such as radiative forcing, photochemistry, new particle formation and phase transitions. In this context, measurements on single particles proved to be very useful for detailed investigations of the properties of the particles studied and of processes affecting them. However, measurements on single nonspherical particles are limited by the difficulties and lack of understanding associated with the optical trapping of such particles. Here, we aim at better understanding the optical trapping of nonspherical particles in air by comparing the motion of an observed nonspherical particle with simulated optical forces and torques. An holographic microscope is used to retrieve the 6D motion of a trapped peanut-shaped particle (3D for translation and 3D for rotation). Optical forces and torques exerted by the optical trap on the peanut-shaped particle are calculated by using FDTD simulations. Most of the main features of the particle motion are in agreement with the calculations while some specific aspects of the particle motion cannot yet be explained.

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“…Since then, many experimental and computational studies have been carried out to understand the properties of the so-called Criegee intermediates and elucidate their role in various chemical environments. [23] We used a time step of 0.1 fs in our simulations.Before proceeding to the unimolecular dynamics, it is useful to consider CH 2 OO at its equilibrium structure, shown in Figure 1 a. CH 2 OO has a C s symmetry, with all atoms in the symmetry plane. [4,5] Important progress was made in synthesizing Criegee intermediates in the laboratory, for example, by using the reaction CH 2 I + O 2 !CH 2 IOO!CH 2 OO + I.…”

mentioning

confidence: 99%

“…As described previously, [19] this method employs parallelization of the computed numerical forces. [23] We used a time step of 0.1 fs in our simulations. For example, on-the-fly dynamics simulations with multireference potentials were carried out by Martínez and co-workers.…”

mentioning

confidence: 99%

Isomerization and Decomposition of a Criegee Intermediate in the Ozonolysis of Alkenes: Dynamics Using a Multireference Potential

Kalinowski

¹

,

Räsänen

²

,

Heinonen

³

et al. 2013

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The isomerization and decomposition dynamics of the simplest Criegee intermediate CH2 OO have been studied by classical trajectory simulations using the multireference ab initio MR-PT2 potential on the fly. A new, accelerated algorithm for dynamics with MR-PT2 was used. For an initial temperature of 300 K, starting from the transition state from CH2 OO→CH2 O2 , the system reaches the dioxirane structure in around 50 fs, then isomerizes to formic acid (in ca. 2800 fs), and decomposes into CO+H2 O at around 2900 fs. The contributions of different configurations to the multiconfigurational total electronic wave function vary dramatically along the trajectory, with diradical contributions being important for transition states corresponding to H-atom transfers, while being only moderately significant for CH2 OO. The implications for reactions of Criegee intermediates are discussed.

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“…[20,21] Coupled-cluster methods also provide an adequate multiconfigurational treatment of the wave function in the dynamics as in the EOM-CCSD study by Shepler et al [22] For larger systems, a semiempirical approach, OM2/ MRCI, is available. [23] We used a time step of 0.1 fs in our simulations.Before proceeding to the unimolecular dynamics, it is useful to consider CH 2 OO at its equilibrium structure, shown in Figure 1 a. CH 2 OO has a C s symmetry, with all atoms in the symmetry plane. In the active space, we include only 12 electrons in 11 orbitals.…”

mentioning

confidence: 99%

“…[20,21] Coupled-cluster methods also provide an adequate multiconfigurational treatment of the wave function in the dynamics as in the EOM-CCSD study by Shepler et al [22] For larger systems, a semiempirical approach, OM2/ MRCI, is available. [23] We used a time step of 0.1 fs in our simulations.…”

mentioning

confidence: 99%

Isomerization and Decomposition of a Criegee Intermediate in the Ozonolysis of Alkenes: Dynamics Using a Multireference Potential

Kalinowski

¹

,

Räsänen

²

,

Heinonen

³

et al. 2013

Self Cite

View full text Add to dashboard Cite

The isomerization and decomposition dynamics of the simplest Criegee intermediate CH 2 OO have been studied by classical trajectory simulations using the multireference ab initio MR-PT2 potential on the fly. A new, accelerated algorithm for dynamics with MR-PT2 was used. For an initial temperature of 300 K, starting from the transition state from CH 2 OO!CH 2 O 2 , the system reaches the dioxirane structure in around 50 fs, then isomerizes to formic acid (in ca. 2800 fs), and decomposes into CO + H 2 O at around 2900 fs. The contributions of different configurations to the multiconfigurational total electronic wave function vary dramatically along the trajectory, with diradical contributions being important for transition states corresponding to H-atom transfers, while being only moderately significant for CH 2 OO. The implications for reactions of Criegee intermediates are discussed.The reactions of ozone with alkenes have been the topic of extensive studies for many years. A widely accepted qualitative mechanism for these reactions was suggested by Criegee and co-workers in 1949. [1] Criegee proposed that the ozonolysis of alkenes proceeds through diradical carbonyl oxides. Since then, many experimental and computational studies have been carried out to understand the properties of the so-called Criegee intermediates and elucidate their role in various chemical environments. [2,3] In particular, these species are currently of major interest in atmospheric chemistry. [4,5] Important progress was made in synthesizing Criegee intermediates in the laboratory, for example, by using the reaction CH 2 I + O 2 !CH 2 IOO!CH 2 OO + I. [6][7][8] The spectroscopic properties of several Criegee intermediates were measured, [9][10][11] and a number of quantum chemical calculations were carried out to understand the electronic structure and chemical bonding of the carbonyl oxides. [12][13][14] These studies suggest a significant role of combined diradical and zwitterionic contributions in determining the chemical properties of the species. Despite the progress made, our understanding of the reactivity and chemical dynamics of Criegee intermediates is still very limited. Experimentally, this is due to difficulties in measuring Criegee intermediates directly, a consequence of the short lifetimes of the species under ambient conditions.The objective of the present work is to study the chemical dynamics of Criegee intermediates by carrying out dynamics simulations on the time scale of the unimolecular processes of a simple carbonyl oxide, CH 2 OO. For this purpose, it is essential to use a high-level ab initio potential that can adequately describe the possible multiconfigurational nature of intermediates in the dynamics, as well as of transition states or other geometries along the trajectories.The possible diradical or zwitterionic character of the electronic states in the course of the dynamics is of key interest. We chose the MR-PT2 method [15] for this purpose, with Dunnings cc-pVDZ [16,17] as basis for this system, and used...

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Femtosecond timescale deactivation of electronically excited peroxides at ice surfaces

Cited by 22 publications

References 83 publications

Morphology and motion of single optically trapped aerosol particles from digital holography

Morphology and motion of single optically trapped aerosol particles from digital holography

Isomerization and Decomposition of a Criegee Intermediate in the Ozonolysis of Alkenes: Dynamics Using a Multireference Potential

Isomerization and Decomposition of a Criegee Intermediate in the Ozonolysis of Alkenes: Dynamics Using a Multireference Potential

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