Abstract. We present a new adiabatic approach for non-perturbative treatment of multiphoton above-threshold detachment (ATD) in intense laser pulses. The electron energy distributions for the pulse detachment are expressed via the detachment transition amplitudes in the monochromatic fields, and the latter are calculated with the help of the adiabatic theory based on the smallness of the laser frequency compared with the electron affinity or ionization potential. The theory is applied to the first study of the pulse shape effects on the multiphoton ATD of the negative ion H^- by 10.6 mu m radiation. Two pulse shapes are considered: a Gaussian pulse and a square pulse with smooth edges. We present the angle-resolved as well as angle-integrated ATD electron energy distributions. They contain oscillatory satellite structures to the main peaks due to interference of the electrons detached on the rising and falling edges of the pulse. Simple analytical formulae describing these subpeak structures are also presented.

Print publication: Issue 12 (28 June 1995)