The Coulomb explosion of carbon dioxide in a 55 fs laser pulse of intensity 1.5-3 × 10 16 W cm −2 has been studied using a variety of techniques based on time-of-flight mass spectroscopy. Covariance mapping has been used to identify Coulomb explosion channels and to measure the associated kinetic energy release. By comparing time-of-flight spectra taken with linearly and circularly polarized light, a clear signature of laser-induced reorientation is found, which is strongest for the lowest Coulombic channel. Ion-momentum imaging coupled with Monte Carlo simulation shows that the zero-point bend-angle distribution is better preserved than for longer laser pulses. However, some residue of the sequential processes dominant in much longer pulses is found.

A fast beam of H2+ ions, produced from a low energy ion accelerator, has been used for the first time in intense laser field experiments. The technique has enabled neutral dissociation products to be analysed and detected for the first time in such studies. Energy spectra of neutral and ionized fragments, product yields as a function of focused laser intensity and angular distributions of neutral dissociation products have been measured. Significant differences are observed between the present results and those obtained from experiments involving neutral H2 molecules. These differences are indicative of the precursor H2 molecule playing an important and hitherto neglected formative role in the laser-induced fragmentation processes.

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A comprehensive study of absolute differential cross sections (DCSs) for electron impact excitation of the bending (010) and unresolved stretching (100 + 001) vibrational quanta of water (H2O) is reported. Eight incident electron energies (E0) in the range 6-20 eV were investigated, and the scattered electron angular range was 10°-135°. Integral cross sections (ICSs) were derived from the corresponding vibrational DCSs using a molecular phase shift analysis technique. The self-consistency of these vibrational ICSs was considered by summing them, at each E0, with available elastic and ionization ICS to provide estimates for the H2O grand total cross section (GTS), which could then be checked against the independent GTSs of Szmytkowski (1987 Chem. Phys. Lett. 136 363) and Sueoka et al (1986 J. Phys. B: At. Mol. Phys. 19 L373). Good agreement was typically found.