The general S-matrix theory of multiphoton ionization is presented. The freedom in the form of the S matrix is discussed and exploited to derive a form that uses the exact dressed state as the initial state of the process. This results in a new S-matrix form, which is then evaluated in an approximate form. The numerical result is identical with a previously obtained one but radically different from that obtained by using the Keldysh–Faisal–Reiss theories.
© 1990 Optical Society of America
Original Manuscript: September 1, 1989
Revised Manuscript: December 13, 1989
Published: April 1, 1990
Predrag Krstić and Marvin H. Mittleman, "S-matrix theory of multiphoton ionization," J. Opt. Soc. Am. B 7, 587-591 (1990)