Study of In2P/In2P− and InP2/InP2− using negative ion zero electron kinetic energy spectroscopy

1994 ◽  
Vol 72 (11-12) ◽  
pp. 1322-1335 ◽  
Author(s):  
Caroline C. Arnold ◽  
Daniel M. Neumark
Keyword(s):  
Excited State ◽  
Kinetic Energy ◽  
Ground State ◽  
Photoelectron Spectra ◽  
Negative Ion ◽  
Electron Affinities ◽  
Electron Kinetic Energy ◽  
First Excited State ◽  
State Frequency ◽  
Term Energy

The zero electron kinetic energy (ZEKE) spectra of In2P− and InP2− are presented and compared to their previously obtained photoelectron spectra (PES) as well as ab initio calculations on analogous species. The threshold spectra, which give high-accuracy electron affinities of 2.400 ± 0.001 eV for In2P and 1.617 ± 0.001 eV for InP2, show well-resolved vibrational structure in the transitions from the ground anion states to the various neutral states. The ZEKE spectrum of In2P− exhibits a fairly extended, 47 cm−1 progression that we assign to the symmetric bend (ν2) in the ground 2B2 neutral state. There is also a 204 cm−1 progression that we assign to the symmetric stretch. The InP2− ZEKE spectrum shows transitions to two electronic states of the neutral. For the ground state, the symmetric stretch mode is the most active in the spectrum, whereas in the excited state, the symmetric bend mode is most active. The InP2 ground-state symmetric stretch frequency is 190 cm−1, and the excited-state symmetric bend frequency is 287 cm−1. An anion ground-state frequency is determined to be 227 cm−1. The term energy of the excited state is determined to be 1.280 ± 0.001 eV. Based on molecular orbital arguments, these frequencies suggest a 2B2 ground InP2 state, a 2A1 first excited state, and a 1A1 anion ground state.

THE HYLLERAAS BINDING ENERGY OF HYDRIDE AND ELECTRON AFFINITIES

2013 ◽  
Vol 12 (04) ◽  
pp. 1350016 ◽  
Author(s):  
EDWARD S. CHEN ◽  
EDWARD C. M. CHEN
Keyword(s):  
Binding Energy ◽  
Electron Affinity ◽  
Ground State ◽  
Photoelectron Spectra ◽  
Negative Ion ◽  
Electron Affinities ◽  
Thermal Electron ◽  
Homonuclear Diatomic Molecules ◽  
Correlation Rules ◽  
Three Body

The normalized electron affinity of the hydrogen atom, is the fundamental measure of anionic electron correlation. The three-body H (−) and AB(−) systems analogous to Efimov three-body bosons support multiple excited states. The first complete set of ground state electron affinities of the main group atoms and homonuclear diatomic molecules are reported using the Hylleraas variational binding energy of the hydride anion. Thermal electron affinities and activation energies for the formation of the 27 bonding states of O 2(−) are reported from electron capture detector and atmospheric pressure negative ion mass spectrometry. These are iterated through magnetron, flame, swarm, electron impact, photodetachment, and negative ion photoelectron spectra to obtain more precise self-consistent values. Electron affinities for NO are similarly reported. These data are used to calculate Herschbach ionic Morse Person electron curves for the 54 O 2(−) and 87 NO (−) states predicted by adiabatic correlation rules. A new ground state adiabatic electron affinity of SF6 3.00(10) eV is determined from negative ion mass spectra.

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.

A meta-analysis and review examining a possible role for oxidative stress and singlet oxygen in diverse diseases

2017 ◽  
Vol 474 (16) ◽  
pp. 2713-2731 ◽  
Author(s):  
Athinoula L. Petrou ◽  
Athina Terzidaki
Keyword(s):  
Oxidative Stress ◽  
Excited State ◽  
Singlet Oxygen ◽  
Ground State ◽  
Meta Analysis ◽  
Common Mechanism ◽  
High Electron ◽  
A Value ◽  
First Excited State

From kinetic data (k, T) we calculated the thermodynamic parameters for various processes (nucleation, elongation, fibrillization, etc.) of proteinaceous diseases that are related to the β-amyloid protein (Alzheimer's), to tau protein (Alzheimer's, Pick's), to α-synuclein (Parkinson's), prion, amylin (type II diabetes), and to α-crystallin (cataract). Our calculations led to ΔG≠ values that vary in the range 92.8–127 kJ mol−1 at 310 K. A value of ∼10–30 kJ mol−1 is the activation energy for the diffusion of reactants, depending on the reaction and the medium. The energy needed for the excitation of O2 from the ground to the first excited state (1Δg, singlet oxygen) is equal to 92 kJ mol−1. So, the ΔG≠ is equal to the energy needed for the excitation of ground state oxygen to the singlet oxygen (1Δg first excited) state. The similarity of the ΔG≠ values is an indication that a common mechanism in the above disorders may be taking place. We attribute this common mechanism to the (same) role of the oxidative stress and specifically of singlet oxygen, (1Δg), to the above-mentioned processes: excitation of ground state oxygen to the singlet oxygen, 1Δg, state (92 kJ mol−1), and reaction of the empty π* orbital with high electron density regions of biomolecules (∼10–30 kJ mol−1 for their diffusion). The ΔG≠ for cases of heat-induced cell killing (cancer) lie also in the above range at 310 K. The present paper is a review and meta-analysis of literature data referring to neurodegenerative and other disorders.

LIFETIME MEASUREMENTS OF STATES IN O18 AND Ne22

1964 ◽  
Vol 42 (6) ◽  
pp. 1311-1323 ◽  
Author(s):  
M. A. Eswaran ◽  
C. Broude
Keyword(s):  
Excited State ◽  
Ground State ◽  
Doppler Shift ◽  
State Transition ◽  
Branching Ratios ◽  
Ground State Transition ◽  
Lifetime Measurements ◽  
Doppler Shift Attenuation ◽  
First Excited State ◽  
Doppler Shift Attenuation Method

Lifetime measurements have been made by the Doppler-shift attenuation method for the 1.98-, 3.63-, 3.92-, and 4.45-Mev states in O18 and the 1.28-, 3.34-, and 4.47-Mev states in Ne22, excited by the reactions Li7(C12, pγ)O18 and Li7(O16, pγ)Ne22. Branching ratios have also been measured. The results are tabulated.[Formula: see text]The decay of the 3.92-Mev state in O18 is 93.5% to the 1.98-Mev state and 6.5% to the ground state and of the 4.45-Mev state 74% to the 3.63-Mev state, 26% to the 1.98-Mev state, and less than 2% to the ground state. In Ne22, the ground-state transition from the 4.47-Mev state is less than 2% of the decay to the first excited state.

Dissociative Electron Attachment Processes in SO2 and NO2

1971 ◽  
Vol 49 (9) ◽  
pp. 1571-1574 ◽  
Author(s):  
D. A. Rallis ◽  
J. M. Goodings
Keyword(s):  
Kinetic Energy ◽  
Ground State ◽  
Electronic Excitation ◽  
Electron Attachment ◽  
Negative Ion ◽  
Dissociation Limit ◽  
Dissociative Electron Attachment ◽  
Zero Kinetic Energy ◽  
Trapped Electron ◽  
Second Peak

A trapped electron apparatus has been used to identify the processes involved in negative ion formation for the triatomic oxides SO2 and NO2. Two O− peaks are observed in SO2 with onset values at 4.2 ± 0.15 and 6.3 ± 0.2 eV, and peak values at 5.0 ± 0.15 and 7.4 ± 0.15 eV, respectively. From kinetic energy analysis of the O− ions, both peaks are found to have the same dissociation limit involving SO in its ground state. For NO2, two dissociative electron attachment peaks are observed with onset values at 1.6 ± 0.2 and 7.3 ± 0.3 eV, and peak values at 3.0 ± 0.2 and 8.1 ± 0.2 eV, respectively. The first broad peak is explained by overlapping contributions from two processes having the same dissociation limit involving ground state NO; they differ only in the amount of kinetic energy possessed by the fragments. The second peak appears to involve electronic excitation of the neutral fragment NO* with zero kinetic energy at onset.

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