PHOTOCHEMISTRY 



255 



indicated by the horizontal Une B at the right. The difference between 

 this energy at dissociation and the energy in the stable position of the 



Velocities 



Fig. 2. — Distribution of energy among a group of molecules: A, at 273°; B, at 373 

 represents extra energy supplied by some external agent. 



E 



>^ 



i- 

 (i) 



C 



Distance Between Atoms 

 FiQ. 3. — Energy relations existing between two atoms as a function of the distance separat- 

 ing their centers. 



molecule represented by C, represents the energy required to dissociate 

 the molecule. It is possible to gain some insight regarding the nature 



