Femtosecond time-resolved wave packet motion in molecular multiphoton ionization and fragmentation

the methyl iodide molecule as quasi-diatomic, the cytindrical symmetry of the problem allows us to place the perpendicular transition dipole vector anywhere in the x-y plane. Lao et al. define their perpendicular transition dipole as being in the (l,l,O) direction, but the algebra is somewhat less cumbersome if the dipole is chosen along either the x or y molecule-fixed axes. The electric vectors for the incident and scattered radiation are given in our coordinate system by 8, = 2 cos 7 + 2 sin 7 8, = 2 cos 8 + P sin 8 (A.4)