Vacuum-ultraviolet photolysis of ethylene oxide

Kawasaki, Masahiro; Ibuki, Toshio; Iwasaki, Masayuki; Takezaki, Yoshimasa

doi:10.1063/1.1680294

Cited by 20 publications

(22 citation statements)

References 22 publications

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“…Figure 1 . This mechanism was confirmed experimentally by Kawasaki et al 27 Interestingly, in this theoretical work, it was suggested that the photochemical ring opening is facilitated by occupation of the second excited state S 2 , while the first excited state S 1 was found to be a nonreactive channel, which can be energetically tapped, however, by the reactive S 2 state. This seems to contradict Kasha’s rule 29 that suggests that the first excited state is the most likely candidate for the initiation of photochemical reactions.…”

Section: Introductionsupporting

confidence: 65%

“…As can be seen from Figure 5 , where the formation probabilities of the reaction products are plotted vs. time for different temperatures, the Gomer–Noyes mechanism is the most dominant process in the NAMD simulations, in agreement with measured data. 27 After 30···40 fs, the ring opening (CH 2 COH 2 formation) is completed in the majority of the excited oxirane molecules. The third reaction step according to Gomer and Noyes, the CH 3 COH formation, is essentially completed for most molecules after about 80 fs.…”

Section: Results and Discussionmentioning

confidence: 99%

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Photochemical Ring Opening of Oxirane Modeled by Constrained Density Functional Theory

2020

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A constrained density functional theory/classical trajectory surface hopping study of the photochemical dissociation of oxirane (CH 2 ) 2 O is presented. The calculations confirm the Gomer–Noyes mechanism for the initial reaction and agree largely with experimental photolysis data including reaction yields. The calculated yields, however, depend both on temperature and its modeling. The timescales of the various reaction steps are well below 100 fs, similar to previous time-dependent density functional calculations. At variance with those, however, the present calculations obey Kasha’s rule, i.e., the photoreaction is initiated in the energetically lowest excited state.

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Section: Introductionsupporting

confidence: 65%

Section: Results and Discussionmentioning

confidence: 99%

Photochemical Ring Opening of Oxirane Modeled by Constrained Density Functional Theory

2020

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“…This is indeed the case: in experiment, the cleavage of the CÀO bond is followed by hydrogen migration to acetaldehyde, which decomposes to a methyl radical and a formyl radical because of the high excess energy (see Figure 6). [6,10,15] The differences between density functional and semi-empirical calculations should not be attributed to the different Hamiltonians used, but to the different basis sets. While semi-empirical methods are usually based on minimal basis sets, we added diffuse basis functions in our density functional calculations.…”

Section: Resultsmentioning

confidence: 99%

Mechanism of Electrocyclic Ring‐Opening of Diphenyloxirane: 40 Years after Woodward and Hoffmann

Friedrichs

Frank

2009

Chemistry A European J

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The photochemistry of diphenyloxirane has been investigated by using static density functional theory and first-principles molecular dynamics. We optimised potential-energy surfaces for both the disrotatory and the conrotatory pathway in the first excited state. Although the disrotatory pathway does not seem to be favoured energetically, we get only the disrotatory product during the molecular dynamics simulations. This can be attributed to the "on-the-fly" description of the electronic structure in a first-principles molecular dynamics simulation. The different photochemical behaviour of aryl oxiranes and unsubstituted oxirane is due to different shapes of the frontier orbitals.

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“…The electronic structure of oxirane (or ethylene oxide) has been carefully studied in previous experimental and theoretical publications [44,73,74]. The main radiationless pathway is summarized as follows: the system is mainly promoted through photoexcitation in the UV to its S 1 electronic excited state (1 1 B 1 (n,3s)) and evolves there until a crossing with the S 2 state [2 1 B 1 (n,3p z )] is reached.…”

Section: Photoexcitation Of Oxirane With a Series Of Short Laser Pmentioning

confidence: 99%

Mixed quantum-classical dynamics with time-dependent external fields: A time-dependent density-functional-theory approach

2010

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A mixed quantum-classical method aimed at the study of nonadiabatic dynamics in the presence of external electromagnetic fields is developed within the framework of time-dependent density functional theory. To this end, we use a trajectory-based description of the quantum nature of the nuclear degrees of freedom according to Tully's fewest switches trajectories surface hopping, where both the nonadiabatic coupling elements between the different potential energy surfaces, and the coupling with the external field are given as functionals of the ground-state electron density or, equivalently, of the corresponding Kohn-Sham orbitals. The method is applied to the study of the photodissociation dynamics of some simple molecules in gas phase.TAVERNELLI, CURCHOD, AND ROTHLISBERGER PHYSICAL REVIEW A 81, 052508 (2010) expand the system wave function at a given time t in a linear combination of static electronic wave functions, (r,R,t) = ∞ J J (r; R) J (R,t), (2.4) with time-dependent coefficients J (R,t), which in the Born-Oppenheimer limit correspond to nuclear wave functions. { J (r; R)} describes a complete set of electronic basis functions that are solutions of the time-independent Schrödinger equation,Ĥ el (r; R) J (r; R) = E el J (R) J (r; R), (2.5) and depend parametrically on the nuclear coordinates R. E el J (R) = H J J (R) is called the J th potential energy surface (PES), which is a function of the nuclear coordinates R. Inserting Eq. (2.4) in the time-dependent Schrödinger Eq. (2.1) and multiplying from the left by * J (r; R) we get, after integration over r, ih ∂ J (R,t) ∂t = − γh 2 2M γ ∇ 2 γ J (R,t) + I H J I (R) I (R,t) + γ Ih 2 2M γ D γ J I (R) I (R,t) − γ,I =Jh 2 M γ d γ J I (R)∇ γ I (R,t), (2.6) 052508-2 MIXED QUANTUM-CLASSICAL DYNAMICS WITH TIME-. . . PHYSICAL REVIEW A 81, 052508 (2010) where H J I (R) = * J (r; R)Ĥ el I (r; R)d r. (2.7) d γ J I (R), the first-order coupling vectors, are defined as d γ J I (R) = { * J (r; R)[∇ γ I (r; R)]}d r, (2.8) and D γ J I (R), the second-order coupling elements, are given by D γ J I (R) = * J (r; R) ∇ 2 γ I (r; R) d r.(2.9)

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Vacuum-ultraviolet photolysis of ethylene oxide

Cited by 20 publications

References 22 publications

Photochemical Ring Opening of Oxirane Modeled by Constrained Density Functional Theory

Photochemical Ring Opening of Oxirane Modeled by Constrained Density Functional Theory

Mechanism of Electrocyclic Ring‐Opening of Diphenyloxirane: 40 Years after Woodward and Hoffmann

Mixed quantum-classical dynamics with time-dependent external fields: A time-dependent density-functional-theory approach

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