Controlling neutral fragmentation yields of methane by femtoseco...

We demonstrate the control of neutral fragmentation of methane (CH4) induced by a Ti:sapphire intense laser pulse (800 nm, 40 fs) by using a pump–probe spectroscopy. Enhancement of the fluorescence emission from the neutral radical CH (A2Δ → X2Π) induced by the intense laser field (~1014 W/cm2) is observed when the wavelength of the probe laser pulse is tuned to 400 nm. The phenomena are explained based on excitation enhancement of the super-excited state of the parent molecule resulting in an i