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Molecular-beam experiments for photodissociation of propenal at 157 nm and quantum-chemical calculations for migration and elimination of hydrogen atoms in systems C3H4O and C3H3O
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10.1063/1.3613636
/content/aip/journal/jcp/135/4/10.1063/1.3613636
http://aip.metastore.ingenta.com/content/aip/journal/jcp/135/4/10.1063/1.3613636

Figures

Image of FIG. 1.
FIG. 1.

TOF spectra of species with m/z = 1 u (H), 2 u (H2), 14 u (CH2), 15 u (CH3), 17 u (OH), 18 u (H2O), 26 u (C2H2), 27 u (C2H3), 28 u (C2H4/CO), 29 u (HCO), 30 u (H2CO), 39 u (C3H3), 41 u (C2HO), and 54 u (C3H2O) upon the photolysis of propenal at 157 nm. Panels show m/z ratios, laboratory angles, and photoionization energies. Top abscissas are only for fragments H and H2. Bottom abscissas are for fragments with m/z = 14–54 u. Open circles denote experimental data and solid lines simulations.

Image of FIG. 2.
FIG. 2.

Product kinetic-energy distributions P(Et). The P(Et)s were derived from the simulations of product TOF spectra on assumption of two-body dissociation except for the product H2 (m/z = 2 u) from the concerted three-body dissociation channel, reaction (4). Et includes kinetic energy of the detected fragment and kinetic energy of its nominal counterparts. All panels have a full scale of 80 kcal mol−1 in abscissas except for the panel of m/z = 2 u that has a full scale of 130 kcal mol−1.

Image of FIG. 3.
FIG. 3.

Diagram of potential-energy surfaces for hydrogen migration and dissociation of C3H4O and C3H3O. TS denotes a transition structure; a hydrogen atom should accompany with TS3–TS21 but is omitted here for brevity. Relative energies including corrections of zero-point energies are given in kcal mol−1. The correlation (dashed-line connection) between TS13 and CH2CCOH (2A″) was not verified with the IRC calculation. The distribution of internal energy (Eint) of C3H3O produced from the photolysis of propenal at 193 nm is also shown therein. The Eint value is calculated for the lowest-lying product channel CH2CHCO (2A) + H. The isomerization from CH2CHCHO to CH3CHCO and CH2CCHOH as well as the dissociation CH2CHCHO → CH2CHCO (2A) + H and CH3CHCO → CH2CHCO (2A″) + H are adapted from Ref. 16.

Image of FIG. 4.
FIG. 4.

Stationary structures of eight C3H3O and two C3H2O isomers optimized at the level of B3LYP/6-311G(d,p). Only pertinent bond lengths (Å) and angles (°) are presented along with each structure. SOMOs of C3H3O and HOMOs of C3H2O are also shown therein.

Image of FIG. 5.
FIG. 5.

Transition structures (TS) of C3H3O molecules optimized at the level of B3LYP/6-311G(d,p). Only pertinent bond lengths (Å) and angles (°) are presented along with each structure.

Image of FIG. 6.
FIG. 6.

Stationary structures of ionic molecules, except CH3CCO+-TS (1A), optimized at the level of B3LYP/6-311G(d,p). Only pertinent bond lengths (Å) and angles (°) are presented along with each structure. CH3CCO+-TS (1A) is a transition structure correlating with CH2CHCO+ (1A) by migration of either hydrogen atoms lying out of the reflection plane of CH3CCO+-TS (1A).

Image of FIG. 7.
FIG. 7.

Low-resolution photoionization spectrum of C3H3O produced from the photolysis of propenal at 193 nm. The spectrum is adapted from Ref. 15. Integral ion signals were recorded at laboratory angle 7°. An optical filter of MgF2 was employed in addition to a noble-gas filter. The small variation of photon flux with photon energy was uncorrected. Arrows indicate the calculated adiabatic ionization potentials of several C3H3O isomers.

Tables

Generic image for table
Table I.

Total energies TE (hartree), zero-point energies ZPE (kcal mol−1), and relative energies Erel (kcal mol−1) of various species in the C3H4O system calculated at the CCSD(T)/6-311+G(3df,2p)//B3LYP/6-311G(d,p) + ZPE[B3LYP/6-311G(d,p)] level of theory.

Generic image for table
Table II.

Adiabatic and vertical ionization potentials (eV) of eight isomers of C3H3O and two isomers of C3H2O calculated at the CCSD(T)/6-311+G(3df,2p)//B3LYP/6-311G(d,p) + ZPE[B3LYP/6-311G(d,p)] level of theory.

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/content/aip/journal/jcp/135/4/10.1063/1.3613636
2011-07-22
2014-04-16
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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Molecular-beam experiments for photodissociation of propenal at 157 nm and quantum-chemical calculations for migration and elimination of hydrogen atoms in systems C3H4O and C3H3O
http://aip.metastore.ingenta.com/content/aip/journal/jcp/135/4/10.1063/1.3613636
10.1063/1.3613636
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