Ethylenes excitation energy

In ethane, C2H6, all of the bonds are normal single bonds. Experiment shows that ethane is a fairly unreactive substance. It reacts only when treated with quite reactive species (such as free chlorine atoms), or when it is raised to excited energy states by heat (as in combustion). Ethylene, on the other hand, reacts readily... 

The basic quantities in this model are Ey the n-ir excitation energy of ethylene, and r, the interaction energy of two basis states with neighboring excited ethylenic-units. Their values are Ey = 7.60 ev, r = -2.54 ev. 

Figure 3 shows the correlation obtained by plotting logio (relative rate) as a function of log Q — 0.5 (e + 0.8) for the seven monomers. Over a range of oxidation rates varying by a factor of 100 the relation predicts the rate from Q,e values to less than a factor of 3. This is less precise than the correlation with excitation energies used for alkyl-subsituted ethylenes (18), but is probably all that can be expected, since the Q,e system is an empirical relation and the assumption of equal reactivities and termination rate constants for primary and secondary peroxy radicals is imprecise (9). 

Fig. 12. Correlation of the rate constant (fc) for the spin orbit relaxation of l(5QPy2) with the excitation energy [ (j3)] of the colliding olefin. (1) Tetramethylethylene. (2) cis-and t/ww-2-Butene. (3) Isobutene. (4) 1-Butene. (5) Propylene. (6) Ethylene. ( 3) = E (units of a resonance integral 3 for a standard C=C bond).133...

In a later study Rauk and Barriel7 have recalculated the twisted ethylene molecule. The approach they took in this calculation, to overcome the difficulty of configuration interaction of a large set, made use of perturbation theory. Their method was recommended for small and medium-size molecules. The excitation energies for ethylene twisted 10°... 

Figure 9-2. Performance of various functionals in the framework of time-dependent DFT for excitation energies of ethylene.

Figure 2-3. The calculated excitation energies to some low-lyjng states of ethylene. The basis set, geometry, and other details are found in Refs. [60, 61, 67, 69]...

Figure 2. Vertical singlet and triplet ir - ir excitation energies of ethylene and the fluoroethylenes as a function of (IP-EA) flOJ...

Cluster Calculations of the Excitation Energies of Ethylene, Butadiene, and Cyclo-pentadiene. 

Problem 9.6 Extend to the tt m.o.s of ethylene the calculation made on page 78 for the energies of the bonding and anti-bonding m.o.s ofELf and conclude that the excitation energy is, with this approximation and ignoring the... 

The 71—>71 excitation energies of the unsaturated hydrocarbons, acetylene, ethylene and benzene are of a similar magnitude as for [43]. They have easy access to the unoccupied n in the bond-formation with the substrate and can be expected, as is also found, to bind with the molecular axis or plane parallel to the surface with a surprisingly constant resulting bond-strength per a-bond formed. 

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