1.916 2 2144 Figure 5.2 Another stable structure for the arginine molecule If the arginine molecule is excited to another electronic state, for example, by promoting a non-bonding electron on its C=O oxygen atom into the neighboring C-O T' orbital. its stable structures will not be the same as in the ground electronic state. In particular, the corresponding C-o distance will be longer than in the ground state, but other internal geometrical parameters may also be modified (albeit probably less so than the C-o distance). Moreover, the chemical reactivity of this excited state of arginine will be different than that of the ground state because the two states have different orbitals available to react with attacking reagents7 1.916 2.144 Figure 5.2 Another stable structure for the arginine molecule. If the arginine molecule is excited to another electronic state, for example, by promoting a non-bonding electron on its C=O oxygen atom into the neighboring C-O p* orbital, its stable structures will not be the same as in the ground electronic state. In particular, the corresponding C-O distance will be longer than in the ground state, but other internal geometrical parameters may also be modified (albeit probably less so than the C-O distance). Moreover, the chemical reactivity of this excited state of arginine will be different than that of the ground state because the two states have different orbitals available to react with attacking reagents