A Photoelectron Investigation of the Peroxide Bond

1975 ◽  
Vol 53 (22) ◽  
pp. 3439-3447 ◽  
Author(s):  
R. S. Brown
Keyword(s):  
Dihedral Angle ◽  
Ground State ◽  
Vibrational Frequencies ◽  
Molecular Orbitals ◽  
Photoelectron Spectra ◽  
Raman Spectroscopic ◽  
Orbital Interactions ◽  
Highest Occupied Molecular Orbitals ◽  
Peroxide Bond

The photoelectron spectra of several peroxides and their interpretation is presented. The effects of substituents is separated from vicinal orbital interactions using as a guideline the effect of similar substitution on the ether analogues. It is found that by comparison of Raman spectroscopic frequencies of the peroxide ground state, and vibrational frequencies for the ion (via pes), that the HOMO of peroxides is antibonding with respect to the O—O linkage. Additionally, the dependence of the splitting of the two highest occupied molecular orbitals on dihedral angle is verified by the pe spectra of several well-defined cyclic peroxides. Finally, the pe spectrum of tetramethyl-1,2-dioxacyclobutane (tetramethyl dioxetane) is presented indicating that it is not unlike other cyclic peroxides.

VUV FRAGMENTATION OF SOME HYDROFLUOROCARBON CATIONS STUDIED USING COINCIDENCE TECHNIQUES

2002 ◽  
Vol 09 (01) ◽  
pp. 153-158 ◽  
Author(s):  
WEIDONG ZHOU ◽  
D. P. SECCOMBE ◽  
R. Y. L. CHIM ◽  
R. P. TUCKETT
Keyword(s):  
Kinetic Energy ◽  
Ab Initio ◽  
Ground State ◽  
Lower Energy ◽  
Lone Pair ◽  
Electronic States ◽  
Photoelectron Spectra ◽  
Highest Occupied Molecular Orbital ◽  
Impulsive Model ◽  
Lone Pair Electrons

Threshold photoelectron–photoion coincidence (TPEPICO) spectroscopy has been used to investigate the decay dynamics of the valence electronic states of the parent cation of several hydrofluorocarbons (HFC), based on fluorine-substituted ethane, in the energy range 11–25 eV. We present data for CF 3– CHF 2, CF 3– CH 2 F , CF 3– CH 3 and CHF 2– CH 3. The threshold photoelectron spectra (TPES) of these molecules show a common feature of a broad, relatively weak ground state, associated with electron removal from the highest-occupied molecular orbital (HOMO) having mainly C–C σ-bonding character. Adiabatic and vertical ionisation energies for the HOMO of the four HFCs are presented, together with corresponding values from ab initio calculations. For those lower-energy molecular orbitals associated with non-bonding fluorine 2pπ lone pair electrons, these electronic states of the HFC cation decay impulsively by C–F bond fission with considerable release of translational kinetic energy. Appearance energies are presented for formation of the daughter cation formed by such a process (e.g. CF 3– CHF +), together with ab initio energies of the corresponding dissociation channel (e.g. CF 3– CHF + + F ). Values for the translational kinetic energy released are compared with the predictions of a pure-impulsive model.

ChemInform Abstract: PHOTOELECTRON SPECTRA AND ORBITAL INTERACTIONS IN METHYLENENORTRIQUINACENES

1978 ◽  
Vol 9 (17) ◽  
Author(s):  
L. N. DOMELSMITH ◽  
K. N. HOUK ◽  
C. R. DEGENHARDT ◽  
L. A. PAQUETTE
Keyword(s):  
Photoelectron Spectra ◽  
Orbital Interactions

STABLE STRUCTURES, ELECTRIC AND MAGNETIC PROPERTIES OF NANOPARTICLES COn(n = 1-6) CLUSTERS: FIRST-PRINCIPLES CALCULATIONS

2013 ◽  
Vol 27 (15) ◽  
pp. 1362007
Author(s):  
JUN LIU ◽  
SHENG-BIAO TAN ◽  
HUI-NING DONG
Keyword(s):  
Magnetic Properties ◽  
Ground State ◽  
First Principles ◽  
Lower Energy ◽  
Magnetic Moments ◽  
Molecular Orbitals ◽  
First Principles Calculations ◽  
Half Metallicity ◽  
Ground State Structures ◽  
Stable Structures

The ground state geometric structures of the nanoparticles or clusters CO n(n = 1-6) were given based on the first-principles calculations. Then the magnetic properties of the clusters CO n(n = 1-6) and ( CO n)-2(n = 1-6) were calculated in system. Results show that their ground state structures are closely related to the numbers of O-ions. These clusters have no magnetic moments and half-metallicity if they are electroneutral. However, they have magnetic moments if they have positive or negative charges. The total magnetic moments of the clusters ( CO n)-2(n = 1-6, but n≠3) are all 2.0000 μB, and all their ions have contributions to the total magnetic moments. The main reason is that the molecular orbitals with lower energy filled with paired electrons and the molecular orbitals with higher energy are occupied by two electrons in parallel.

Assignment of the valence molecular orbitals of cis-[PtR2L2] complexes: UV photoelectron spectra and SCF-MS-X.alpha. calculations

1989 ◽  
Vol 28 (1) ◽  
pp. 1-2 ◽  
Author(s):  
Dong Sheng Yang ◽  
G. Michael Bancroft ◽  
John D. Bozek ◽  
R. J. Puddephatt ◽  
John S. Tse
Keyword(s):  
Molecular Orbitals ◽  
Photoelectron Spectra

Orbital interactions. IX. The effect of remote substituents on the electrophilic nitration of a series of 11-substituted exo-hexahydro-7,10-methanofluoranthenes

1980 ◽  
Vol 33 (4) ◽  
pp. 795 ◽  
Author(s):  
MJ Oliver ◽  
HK Patney ◽  
MN Paddon-Row
Keyword(s):  
Product Distribution ◽  
Molecular Orbitals ◽  
Orbital Interactions ◽  
Opposite Result ◽  
Field Effects ◽  
Methoxy Substituent ◽  
Salient Features ◽  
Scf Calculations

Product distribution and the relative rates of nitration (Cu(NO3)2,3H2O/Ac2O) of a series of 11-substituted exo-hexahydro-7,10- methanofluoranthenes, (8), (9b), (10) and (11b), and acenaphthene, (12), have been determined. It was observed that a syn-methoxy substituent, as in (11b), greatly enhanced the reactivity of the acenaphthene ring towards nitration compared with unsubstituted (8), the α position being activated more than the γ position. Precisely the opposite result was obtained for the nitration of the ketone (10). These results are explained in terms of the consequences of through- space orbital interactions (OITS), operating between the molecular orbitals of the 11-substituent and those of the acenaphthene ring; a PMO model is used for the nitration reaction. The results of INDO MO SCF calculations on the water-acenaphthene complex (22) and the formaldehyde-acenaphthene complex (23), which are intended to mimic the salient features of (11b) and (10) respectively, lend support to the OITS proposal. However, alternative proposals, based on field effects (in the case of (10)) and on the formation of a complex (24) for the nitration of (11b), are also discussed.

scholarly journals Molecular Structure Modulated Trap Distribution and Carrier Migration in Fluorinated Epoxy Resin

Molecules ◽  
2020 ◽  
Vol 25 (13) ◽  
pp. 3071 ◽  
Author(s):  
Jin Li ◽  
Yufan Wang ◽  
Zhaoyu Ran ◽  
Hang Yao ◽  
Boxue Du ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Surface Charge ◽  
Epoxy Resin ◽  
Mobility Model ◽  
Molecular Orbitals ◽  
Chemical Calculation ◽  
Dissipation Process ◽  
Highest Occupied Molecular Orbitals ◽  
Lowest Unoccupied Molecular Orbitals ◽  
Positively Charged

Surface charge accumulation on epoxy insulators is one of the most serious problems threatening the operation safety of the direct current gas-insulated transmission line (GIL), and can be efficiently inhibited by the surface modification technology. This paper investigated the mechanisms of fluorination modulated surface charge behaviors of epoxy resin through quantum chemical calculation (QCC) analysis of the molecular structure. The results show that after fluorination, the surface charge dissipation process of the epoxy sample is accelerated by the introduced shallow trap sites, which is further clarified by the carrier mobility model. The electron distribution probability of the highest occupied molecular orbitals (HOMO) under positive charging and the lowest unoccupied molecular orbitals (LUMO) under negative charging shows distinctive patterns. It is illustrated that electrons are likely to aggregate locally around benzenes for the positively charged molecular structure, while electrons tend to distribute all along the epoxy chain under negatively charging. The calculated results verify that fluorination can modulate surface charge behaviors of epoxy resin through redesigning its molecular structure, trap distribution and charging patterns.

Theoretical Determination of the Ground State Geometry of 1.3.5-Triphenylbenzene

1984 ◽  
Vol 39 (12) ◽  
pp. 1250-1254 ◽  
Author(s):  
J. Ciosłowski
Keyword(s):  
Dihedral Angle ◽  
Ground State ◽  
Reasonable Agreement ◽  
Uv Spectrum ◽  
Theoretical Determination ◽  
Transition Energies ◽  
Benzene Rings ◽  
First Ionization Potential ◽  
Ground State Geometry

The geometry and electronic structure of 1.3.5-triphenylbenzene (TPB) has been determined by semiempirical quantum methods. Using the MNDO approach, the salient dependencies of the first ionization potential, the intramolecular distances and the bond angles on the dihedral angle between the planes of the TPB benzene rings were established. By an application of the CNDO/S method the UV spectrum of TPB was calculated. A comparison of the calculated transition energies with the values observed in the absorption spectrum yields 45° for the dihedral angle, which is in reasonable agreement with the available experimental data.

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