Direct observation of super-excited states in methane created by a femtosecond intense laser field

Abstract

We report, for the first time, a direct observation of the super-excited states of CH(4) in femtosecond intense laser fields using a pump (800 nm)-probe (1338 nm) technique. An unambiguous depletion of the CH (A (2) Delta -> X (2)Pi) fluorescence signal as a function of the delay time is attributed to the de-excitation of the super-excited states by the probe laser pulse. The lifetime of the super-excited state is measured to be about 160 fs.