Intense laser-induced decomposition of mass-selected 2-, 3-, and 4-methylaniline cations

Photodecomposition processes of 2-, 3-, and 4-methylaniline cations induced by a moderately intense (∼1011 W/cm2) visible nanosecond laser field and an intense (∼1015 W/cm2) UV femtosecond laser field have been investigated using a tandem mass spectrometer. Highly unsaturated fragment cations such as C 6 H 2 + and C 6 H 3 + are dominantly produced by the nanosecond laser, while less unsaturated smaller fragment cations such as C 3 H 3 + , C 4 H 4 + , and C 5 H 5 + are produced mainly by the femtosecond laser. Ab initio calculations have also been performed to estimate the stable geometrical structures of C 6 H 2 + and C 6 H 3 + and those of possible intermediate ring compounds for discussing the photodecomposition pathways in intense laser fields.