The high-resolution ionization spectroscopy of DNA bases is reported for the first time. Vacuum-UV mass-analyzed threshold ionization (VUV-MATI) spectrum of jet-cooled thymine provides not only the most precise ionization potential but also its vibrational structure in the ground cationic state.

Multiphoton/tunnel ionization of benzene, interacting with strong Ti:sapphire laser pulses, to doubly charged ions was studied. In contrast to previously published results on multiphoton/tunnel ionization of atoms and molecules, it was demonstrated that double ionization of benzene occurs mainly through non-sequential processes.

It is shown that existing problems with the formal theory of ionization can be effectively resolved. An integral representation for the ionization amplitude free of ambiguity and divergence problems is given. Moreover, the ionization amplitude in the new formulation is shown directly to have an ideal form for practical calculations.

We report an original optical method providing the probability of molecular ionization induced by femtosecond laser pulses. The approach consists of exploiting molecular alignment to extract reliable information about ionization. The cross defocusing technique implemented for this purpose reveals a sensitivity with respect to postpulse alignment, as well as to the free electron density induced ...

Plasma ionization composition and level population calculations require, in particular, the cross sections of direct ionization from each quantum state into each state which may be generated by means of removal of any electron. We analysed published data and propose here an empirical formula for cross sections of direct electron-impact ionization of positive atomic ions. The cross sections give...

When an electron from a diatomic molecule undergoes tunneling-rescattering ionization, a novel form of destructive interference can be realized that involves all four geometric orbits that are available to the electron when it is freed, because both ionization and rescattering may take place at the same or at different centers. We find experimentally and confirm theoretically that in orientatio...

Published experimental photon and electron impact ionization cross sections of CH4 have been reviewed and analyzed. Absolute partial ionization oscillator strengths (fij) for CH4 , CH + 3 , CH + 2 , CH , H and H2 have been obtained. Electron impact ionization cross sections are recommended based on agreement between the oscillator strength values derived from photoionization and electron impact...

Recently performed experiments 1 have demonstrated that half-cycle pulses (HCPs), i.e. unimodular electromagnetic pulses, are a useful new spectroscopic tool which is particularly well suited for investigating the dynamics of weakly bound Rydberg electrons. Typically their pulse durations range from the subpicosecond to the nanosecond regime and these pulses have already been produced with elec...