Control of Nuclear Dynamics with Strong Ultrashort Laser Pulses

Geißler, Dominik; Marquetand, Philipp; González‐Vázquez, Jesús; González, Leticia; Rozgonyi, Tamás; Weinacht, Thomas

doi:10.1021/jp306686n

Cited by 35 publications

(42 citation statements)

References 41 publications

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“…Dihalomethanes have been utilized in cyclopropanation reactions of alkenes due to their unique photochemistry in solution. [3][4][5][6][7][8][9] The potential for optical control [10][11][12][13][14][15][16] arises from the manifold of electronic states involved 17 and the rapid photochemistry that is competitive with internal deactivation and redistribution of the incident energy. 18,19 In general, UV absorption in dihalomethanes promotes an electron from a nonbonding halogen orbital (n X ) into a halogen-carbon antibonding orbital (σ * C-X ), causing cleavage of the carbon halogen bond.…”

Section: Introductionmentioning

confidence: 99%

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Solvent dependent branching between C-I and C-Br bond cleavage following 266 nm excitation of CH2BrI

Anderson

Spears

Wilson

et al. 2013

The Journal of Chemical Physics

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It is well known that ultraviolet photoexcitation of halomethanes results in halogen-carbon bond cleavage. Each halogen-carbon bond has a dominant ultraviolet (UV) absorption that promotes an electron from a nonbonding halogen orbital (nX) to a carbon-halogen antibonding orbital (σ*C-X). UV absorption into specific transitions in the gas phase results primarily in selective cleavage of the corresponding carbon-halogen bond. In the present work, broadband ultrafast UV-visible transient absorption studies of CH2BrI reveal a more complex photochemistry in solution. Transient absorption spectra are reported spanning the range from 275 nm to 750 nm and 300 fs to 3 ns following excitation of CH2BrI at 266 nm in acetonitrile, 2-butanol, and cyclohexane. Channels involving formation of CH2Br + I radical pairs, iso-CH2Br-I, and iso-CH2I-Br are identified. The solvent environment has a significant influence on the branching ratios, and on the formation and stability of iso-CH2Br-I. Both iso-CH2Br-I and iso-CH2I-Br are observed in cyclohexane with a ratio of ~2.8:1. In acetonitrile this ratio is 7:1 or larger. The observation of formation of iso-CH2I-Br photoproduct as well as iso-CH2Br-I following 266 nm excitation is a novel result that suggests complexity in the dissociation mechanism. We also report a solvent and concentration dependent lifetime of iso-CH2Br-I. At low concentrations the lifetime is >4 ns in acetonitrile, 1.9 ns in 2-butanol and ~1.4 ns in cyclohexane. These lifetimes decrease with higher initial concentrations of CH2BrI. The concentration dependence highlights the role that intermolecular interactions can play in the quenching of unstable isomers of dihalomethanes.

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Section: Introductionmentioning

confidence: 99%

“…[10][11][12]14 Strong field control experiments of CH 2 BrI have been undertaken in the gas phase. 13,16 These experiments used multiphoton ionization to produce CH 2 BrI + and explore the subsequent control FIG. 1.…”

Section: Introductionmentioning

confidence: 99%

Solvent dependent branching between C-I and C-Br bond cleavage following 266 nm excitation of CH2BrI

Anderson

Spears

Wilson

et al. 2013

The Journal of Chemical Physics

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“…A recent experiment showed the evidence of O 2 formation from CO 2 molecules after UV excitation through the detection of C + [5]. So far, O 2 formation from CO 2 has not been directly observed.In the past decade, intense ultrashort laser pulses have been successfully applied to trigger and control molecular reactions such as dissociation and isomerization [6][7][8][9][10][11][12][13][14][15]. When a molecule interacts with a strong laser field, electrons from outer molecular orbitals can be excited or removed through tunneling or over-the-barrier ionization which may prepare the molecule in an excited state or a state with a certain charge.…”

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confidence: 99%

Molecular oxygen observed by direct photoproduction from carbon dioxide

et al. 2017

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Oxygen (O2 ) is one of the most important elements required to sustain life. The concentration of O2 on Earth has been accumulated over millions of years and has a direct connection with that of CO2 . Further, CO2 plays an important role in many other planetary atmospheres. Therefore, molecular reactions involving CO2 are critical for studying the atmospheres of such planets. Existing studies on the dissociation of CO2 are exclusively focused on the C-O bond breakage. Here we report first experiments on the direct observation of molecular Oxygen formation from CO2 in strong laser fields with a reaction microscope. Our accompanying simulations suggest that CO2 molecules may undergo bending motion during and after strong-field ionization which supports the molecular Oxygen formation process. The observation of the molecular Oxygen formation from CO2 may trigger further experimental and theoretical studies on such processes with laser pulses, and provide hints in studies of the O2 and O + 2 abundance in CO2 -dominated planetary atmospheres.PACS numbers: 33.80. Gj, 42.50.Hz, O 2 production is one of the most important processes for the biosphere of the Earth.Oxygen molecules are mainly generated via the photosynthesis by green plants and algae from carbon dioxide and water:. CO 2 is not only important for the atmosphere on Earth, it is also the dominant compound of the atmosphere on other planets, such as Mars and Venus. One of the most crucial tasks for the quest to establish a human settlement on Mars is the production of O 2 [2]. Because more than 95% of the atmosphere on Mars is CO 2 , it will be extremely helpful if O 2 can be produced directly from CO 2 . In the past, it was observed that dissociation of CO 2 via absorption of photons leads to carbon monoxide (CO) and oxygen atoms (O) [3]. However, theoretical simulations suggested the possibility of generating O 2 through the dissociation of a CO 2 molecule [4]. A recent experiment showed the evidence of O 2 formation from CO 2 molecules after UV excitation through the detection of C + [5]. So far, O 2 formation from CO 2 has not been directly observed.In the past decade, intense ultrashort laser pulses have been successfully applied to trigger and control molecular reactions such as dissociation and isomerization [6][7][8][9][10][11][12][13][14][15]. When a molecule interacts with a strong laser field, electrons from outer molecular orbitals can be excited or removed through tunneling or over-the-barrier ionization which may prepare the molecule in an excited state or a state with a certain charge. As a consequence, the excited or ionized molecule may undergo severe geometrical reconfiguration and may also break into several fragments or form new chemical bonds. Because of the importance of CO 2 in many research disciplines, strongfield induced reactions of CO 2 have been experimentally studied with ultrashort lasers by several research groups.However, these studies mainly focused on the topic of ionization and dissociation [16]. In this paper, for the first...

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“…We observe that, basically,t hree RSRSs are of importance:t hose with the oxygen atom having eight, nine and ten electrons or (O) 0 (CHR) 0 ,( O) À1 (CHR) + 1 and (O) À2 (CHR) + 2 structures, respectively.A tt he bottom of the Figure, we plot the EDFs of HCO-CH 3 and HCO-OH with regard to that of formaldehyde. 7 It is clear how acetaldehyde presentsg ood transferability,a so pposed to formic acid, where the (O) À2 (CHR) + 2 is endowed with ag reater importance than that in formaldehyde at the expense of the (O) 0 (CHR) 0 and (O) À1 (CHR) + 1 forms.…”

Section: Electron Distribution Functionmentioning

confidence: 99%

How Electronic Excitation Can be Used to Inhibit Some Mechanisms Associated to Substituent Effects

et al. 2016

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Despite the fact that transferability and chemistry go hand in hand, transferability studies in electronically excited states (EESs) are normally omitted, although these states are becoming extremely important in modern processes and applications. In this work, it is shown that this kind of studies can be used to understand how substituent effects can be modified in EESs. Thus, for example, the analysis of the carbonyl oxygen transferability in different HCO-R molecules allowed us to find that the nO→πCO* excitation can be used to break the π conjugation associated to the resonance substituent effect. Moreover, as a direct consequence, the oxygen transferability is enhanced in the first electronically excited state.

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Control of Nuclear Dynamics with Strong Ultrashort Laser Pulses

Cited by 35 publications

References 41 publications

Solvent dependent branching between C-I and C-Br bond cleavage following 266 nm excitation of CH2BrI

Solvent dependent branching between C-I and C-Br bond cleavage following 266 nm excitation of CH2BrI

Molecular oxygen observed by direct photoproduction from carbon dioxide

How Electronic Excitation Can be Used to Inhibit Some Mechanisms Associated to Substituent Effects

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