Ionization potential, vertical

Table 5. The ionization potentials (vertical) of a number of halofluoro-carbons...

The electron alfinity and ionization potential can be either for vertical excitations or adiabatic excitations. For adiabatic potentials, the geometry of both ions is optimized. For vertical transitions, both energies are computed for the same geometry, optimized for the starting state. 

Another technique for obtaining an ionization potential is to use the negative of the HOMO energy from a Hartree-Fock calculation. This is called Koopman s theorem it estimates vertical transitions. This does not apply to methods other than HF but gives a good prediction of the ionization potential for many classes of compounds. 

The Lowest Vertical Ionization Potentials (eV) of Benzo Annelated Heterocycles... 

The vertical ionization potentials from the photoelectron spectra of some thiirane and thiirene derivatives are given in Table 3. A Walsh localized scheme of bonding is generally preferred. There is a strong hyperconjugative interaction in thiirene 1,1-dioxides between the occupied C=C tt-MO and the occupied SO2 pure sulfur d-AO. Thiirene oxides are suggested to be less aromatic than cyclopropenones and tropone. 

Benzo[b]furan, 2,3-dihydro-2-phenyl-synthesis, 4, 697 Benzo[b]furan, 2,3-dihydroxy-tautomerism, 4, 37 Benzo[6]furan, 4,6-dimethoxy-acylation, 4, 606 Benzo[6]furan, 2,3-dimethyl-acetylation, 4, 606 bromination, 4, 605 photooxygenation, 4, 642 Benzo[b]furan, 5,6-dimethyl-2,3-diphenyl-applications, 4, 709 Benzo[b]furan, 1,3-diphenyl-vertical ionization potential, 4, 587 Benzo[b]furan, 2-ethoxy-5-hydroxy-synthesis, 4, 127... 

Tetraselenafulvalene, hexamethylene— see A-2,2 -Bi-4,5-trimethylene-1,3-diselenolylidene Tetraselenafulvalenes H NMR, 6, 958 mass spectra, 6, 955 PE spectra, 6, 953 Raman spectra, 6, 954, 955 synthesis, 6, 971 UV spectra, 6, 952 vertical ionization potential, 6, 953 Tetraselenafulvalenes, diphenyl-synthesis, 6, 963... 

The ionization being accompanied by a vibrational excitation, the fine structure of bands can be exploited for determination of vibrational levels of an ionized system in the ground and excited states. Of course, the first (0-0) and the strongest vibrational bands are the most important because they determine adiabatic and vertical ionization potentials of radicals. 

Vertical Ionization Potential and Transition Energies of the YbF Molecule (in cm-1), Computed Using the RASCI Method... 

FIGURE 4.1 Illustration of adiabatic and vertical ionization potentials. Adiabatic I.P. refers to the energy difference between the lowest quantum states of the molecule and its positive ion. Often, Franck-Condon (vertical) transitions lead to a higher value, the vertical ionization potential. 

The spectra and calculations all led to the conclusion that there is an usually large interaction between both the 7T and lone-pair orbitals in the carbonyl portion of the molecule with the n and a orbitals of the olefin portion. The first ionization potential (9.57 eV) involves ionization of an electron from the oxygen lone pair, whereas the second (11.19 eV) involves ionization of an electron from the olefin rr-bond. The most vertical ionization is from the 7 ax MO (16.11 eV), the second lone-pair orbital on oxygen. 

Fig. 4 (a) Correlation of the standard oxidation potentials E%r of various alkylbenzenes with the irreversible CV peak potentials Ep at scan rate v = 100 mV s. (b) Correlation of the standard oxidation potentials r of various alkylbenzenes with the vertical ionization potentials IP. Numbers refer to the aromatic hydrocarbons identified in Tables I and III in Ref. 8. Reproduced with permission from Ref. 8. 

Fig. 5 Global correlation of the oxidation potentials Eox (V versus SCE) with the vertical ionization potentials IP (eV) of various types of organic donors identified in Table 3.

The vertical ionization potential of the electron donor is represented by Ip, and the electron affinity of the acceptor by E. ... 

Vertical ionization potentials of the rcs orbital in substituted benzenes were correlated with the LDRA equation (equation 70) to give the regression equation ... 

Despite the strong MO mixings indicated by the Ae splittings, one may question to what extent the MO energy variations are reflected in measurable physical properties. As described in Section 3.2.4, the interactions of filled NBOs lead to symmetric second-order energy shifts with no net effect on total energy, wavefunc-fion, and other properties. However, the assumptions of Koopmans theorem imply that the vertical ionization potential (IP) is related to HOMO orbital energy by... 

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