Double-charge-transfer spectroscopy was used to measure the double-ionization energies of chromium hexacarbonyl and molybdenum hexacarbonyl molecules to triplet electronic states of the corresponding dications. The spectra were interpreted using data calculated using a modified MSX alpha method. The measured double-ionization energy to the ground triplet state is 22.8 +/- 0.5 eV for Cr(CO)(6) and 22.4 +/- 0.5 eV for Mo(CO)(6)(;) both values match, within experimental error, an earlier measurement of 22.8 +/- 0.5 eV for W(CO)(6). The spectra for the three hexacarbonyls are remarkably similar, probably reflecting that the electronic structures of the three molecules are almost identical in the valence region. The similarity is reflected in the calculated data; the Coulomb repulsions between the two positive holes which characterize the dictations' states are 4.54, 4.44 and 4.45 eV for Cr(CO)(6)(2+), Mo(CO)(6)(2+) and W(CO)(6)(2+), respectively. These values correspond to the repulsive energy for two single charges separated by just over 3 Angstrom, this separation being consistent with the size of the molecules.

A system for combining normal and reversed phase high-performance liquid chromatography solute focusing with packed column supercritical fluid chromatography and supercritical fluid chromatography-mass spectrometry has been developed. The technique has been used to identify paracetamol and stanozolol in spiked plasma extracts and its utility for the analysis of a sample from a process waste stream is illustrated.

The double-ionization energies of the eight chlorofluoroethane molecules have been measured by double-charge-transfer spectrometry. Several peaks were observed in most of the spectra giving information about the energies required to populate electronically excited states (or groups of states) of the dications as well as those to the ground states. In addition to the experimental study, the vertical double-ionization energies to the lowest triplet levels of the dications were calculated. In general, the calculated values are lower than those determined experimentally, but the addition of a uniform shift of 0.4 eV to them brings all calculated data to within ±0.7 eV of those measured. This agreement is quite good since the uncertainty associated with the measured double-ionization energies to the ground states is ±0.5 eV.

Double-charge-transfer spectrometry was used to measure double-ionization energies to ground and electronically excited states of various chlorobenzenes. Since OH+ was the projectile ion used in these experiments, it is probable that triplet states of the dications were populated because of spin conservation in the double-electron-capture reactions which are the basis of this type of spectrometry. The lowest double-ionization energies for all the molecules studied are within +/- 0.3 eV of 25.9 eV, except that for 1,3-dichlorobenzene, which is at 26.6 eV. In general, double-ionization energies to three higher lying states (or groups of states) were measured for each molecule. The energies of these states are the same, within experimental uncertainties, for the three trichlorobenzenes, two tetrachlorobenzenes and pentachlorobenzene dications, suggesting that they have the same or very similar distributions of triplet-state energies.

Tungsten hexacarbonyl was investigated by double-charge-transfer (DCT) spectroscoPy, and the double-ionization energies to ground and electronically excited states of W(CO) 6 2+ determined. The double-ionization energies corresponding to the first two distinct peaks in the spectra are 22.8 ± 0.3 eV and 28.5 ± 0.3 eV, but numerous overlapping peaks at higher energies are evident. It is shown that the DeI spectra can explain the main features of a previously determined (J. Am. Soc. Mass Spectrom. 1990, 1, 16–27) internal energy distribution curve for W(CO) 6 2+ ions formed by 70-eV electron ionization of W(CO)6 molecules.