Theoretical and experimental investigations of ionization-dissociation of polyatomic molecules

The Keldysh theory originally developed for the ionization of 1s state of hydrogen atom has been generalized for molecules by introducing the molecular orbital theory and the Born-Oppenheimer approximation. Ionization and dissociation mechanisms of cyclopentanone in the intense 800 nm laser field (10
¹³
to 10
¹⁴
W/cm
²
) have been experimentally investigated by using a method of molecular beam and time-of-flight mass spectrometer (TOF-MS). Singly-charged parent ion and numerous fragment ions are observed in the mass spectra, which are analyzed by using the molecular Keldysh theory.