| Abstract
| - Field ionization of acetone, butanone, and 3-pentanone in an intense laser field is experimentally investigatedby using a femtosecond laser and a time-of-flight mass spectrometer. Theoretically, the ionization process istreated by using a molecular orbital-based model. The nonbonding Px electron in the oxygen atom is consideredas the most feasibly ionized electron and the x axis as the most feasibly ionized vector. The electrostaticpotential is obtained by combining the ab initio potential of the molecule and the external potential. Thetunneling probability of the Px electron through the potential barrier is numerically calculated by the transfermatrix method. The ionization probability is modified by the spatial and temporal corrections for a pulsedlaser beam, and the total ion yields can thus be obtained. The calculated laser power dependence of the ionyield agrees well with the experimental data measured in the range of 3.5 × 1013−1.2 × 1014 W/cm2.
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