We present here a phenomenological model calculation that exhibits the realistic qualitative behavior of multiphoton excitation and dissociation of polyatomic•molecules. It is also used to show that at least theoretically multiphoton excitation of molecule's is not equivalent to thermal heating.

Three and four center unimolecular elimination reactions of HCl have been investigated for CHF2Cl, CHFCl2, CH3CCl3, CH3CF2Cl, and CHClCF2 in a molecular beam experiment using infrared multiphoton absorption to energize the molecule. The translational energy distributions obtained in this work show that the average translational energy released to the fragments is around 8–12 kcal/mole, except for the three center elimination reaction from CHClCF2, which gives a value of 1 kcal/mole. In four center eliminations, the translational energy released is less than 20% of the potential energy barrier of the back reaction. This is somewhat less than previous indications that approximately 30% of the potential energy barrier of the exit channel in four center reactions should be released into translation.

This is a Library Circulating Copy which may be borrowed for two weeks. For a personal retention copy} call Tech. Info. Division} Ext. 6782.