Ionization of ethane, butane, and octane in strong laser fields

Strong-field photoionization of ethane, butane, and octane are reported at intensities from 1014 to 1017 W/cm2. The molecular fragment ions, C+ and C2+, are created in an intensity window from 1014 to 1015 W/cm2 and have intensity-dependent yields similar to the molecular fragments CmHn+ and CmHn2+. In the case of C+, the yield is independent of the molecular parent chain length. The ionization of more tightly bound valence electrons in carbon (C3+ and C4+) has at least two contributing mechanisms, one influenced by the parent molecule size and one resulting from the tunneling ionization of the carbon ion.