Helicopter reactions

Helicopter reactions phase-change rule, 459-460 quantitative photochemical analysis,... 

The next simplest loop would contain at least one reaction in which three electron pairs are re-paired. Inspection of the possible combinations of two four-electron reactions and one six-electron reaction starting with CHDN reveals that they all lead to phase preseiwing i p loops that do not contain a conical intersection. It is therefore necessary to examine loops in which one leg results in a two electron-pair exchange, and the other two legs involve three elechon-pair exchanges fip loops). As will be discussed in Section VI, all reported products (except the helicopter-type elimination of H2) can be understood on the basis of four-electron loops. We therefore proceed to discuss the unique helicopter... 

Seeing the whole picture taking a helicopter view, managing time and other resources, anticipating reactions from stakeholders, spotting links and unexpected events. 

In contrast to the vibrational effect, the rotational effect on hydrogen dissociation on Cu is much less understood, until very recently. Most 3D quantum calculations have used the plane rotor model, which is not appropriate for studying rotational effects. The studies of Refs. 113, 114, and 117 using the spherical rotor treatment have obtained important results on the effect of rotational orientation and the nuclear symmetry. The rotational orientational effect is clearly shown in Fig. 15, where reaction probabilities for different initial rotational orientation states are plotted as a function of kinetic energy. Significant enhancement of reaction probability is seen for the state with j = m ( helicopter mode) while the m = o ( cartwheel mode) is least effective for dissociation. 

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