WAVE-FUNCTION SPLITTING TECHNIQUE FOR CALCULATING ABOVE-THRESHOLD IONIZATION ELECTRON-SPECTRA

In intense laser fields, atoms and molecules can absorb many more phot ons than required for ionization. This phenomenon is called above-thre shold ionization (ATI) and it shows up in kinetic energy spectra of io nized electrons. The presence of very high energy photoelectrons neces sitates the use of extremely large grids in numerical simulations base d on the full time-dependent Schrodinger equation. We show that by usi ng a wave function splitting scheme one can circumvent the problem of large grids and thus obtain accurate multiphoton photoelectron spectra . This scheme will be very useful in studies of ATI spectra generated by molecules in intense laser fields. We illustrate this method for a one-dimensional model of the H atom in intense laser fields. (C) 1996 John Wiley & Sons, Inc.