Chirping dependent ionization and dissociation of methane in an intense femtosec

We studied the ionization and dissociation of polyatomic molecule methane in an intense femtosecond laser field with wavelength of 810 nm and intensities ranging from 1.4×10^(14) to 2.6×10^(15) W/cm2 by mass spectroscopy. Abundant fragment ions were observed in addition to the strong parent ion. The