Laser-induced dissociation and explosion of methane and methanol

Femtosecond laser-field-induced dissociation and explosion of polyatomic molecules methane and methanol were experimentally investigated by using a time-of-flight mass spectrometer and a chirped pulse amplifier laser. Both linearly polarized and circularly polarized femtosecond laser pulses were used. The intensity varied from 6 x 10(13) to 3 x 10(15) W cm(-2). Strong molecular ions, singly charged fragmental ions and highly charged atomic ions were observed for both methane and methanol. The singly charged fragmental ions had a similar dependence on laser intensity compared with the molecular ions. This indicated that the ionization of the inner-valence electron led to the formation of highly excited molecular ions that rapidly dissociated into the singly charged fragmental ions. The highly charged atomic ions were evidence of Coulomb explosion, The kinetic energies of the atomic carbon ions were almost zero for methane and relatively large for methanol. This indicated that the explosion of polyatomic molecules methane and methanol was a concerted process and all the bonds in the molecules were broken simultaneously.OpticsPhysics, Atomic, Molecular & ChemicalSCI(E)EI21ARTICLE112575-25823