Probing the lifetimes of internally excited amyl nitrite cations.

The photoelectron spectrum shows that multiphoton ionization of amyl nitrite, C(5)H(11)ONO, using ultrafast laser pulses deposits up to 3.7 eV of energy into internal degrees of freedom. As a result, the molecules fragment to produce various daughter ions of masses 87, 71, 60, 57, 41, 30, 29, and 27. Absorption of an additional photon with 3 eV of energy by the ions yields transients with picosecond decay times, revealing the time scale of the decomposition dynamics of the initially prepared parent ion. Each mass peak has a distinct time constant, in the range of 1.2 to 7.9 ps, emphasizing the dependence of the fragmentation mechanism on the ion internal energy.