Heavy atom perturbation intermolecular

The effect is observed when the heavy atom is substituted in the molecule (intramolecular effect) as also when the molecule collides with a heavy atom containing perturber (intermolecular or external effect). The dramatic enhancement of S —T transition due to intramolecular and intermolecular heavy atom perturbations are respectively shown in Figure 3.8 for chloronaphthalenes in ethyl iodide and other perturbants. Molecular oxygen has a perturbing effect on S — T absorption spectra of organic molecules in solution. Under a pressure of 100 atm of Os, well defined... 

H-abstraction intramolecular, 378 Half-value concentration, 181 Half-band width, 69 Half quenching concentration, 173 Hamiltonian operator, 65 perturbing, 67 Hammet equation, 110 He-Ne laser, 318 Heavy atom perturbation, 70 external, 145 intermolecular, 71 intramolecular, 71... 

However, forbidden transitions are still observed in many molecules, because intramolecular or intermolecular perturbations cause the rules to relax considerably. Singjet-triplet transitions, for instance, occur with increased intensity in the presence of paramagnetic substances such as O2 or NO or in solvents such as C2H5I that contain heavy atoms. 

---