James A. Kinsinger

Developments in analytical fourier-transform mass spectrometry

Abstract Development of a differentially-pumped, dual-cell geometry, coupled with the evolution of pulsed-laser desorption and Cs + -secondary-ion mass spectrometric (s.i.m.s.) desorption methods, has improved the analytical utility of Fourier-transform mass spectrometry (F.t.m.s.). A survey of applications and performances obtained in our laboratories is presented. Among the topics covered are ultra-high-resolution electron-impact and chemical-ionization mass spectra, gas chromatography/F.t.m.s. performance, pulsed Cs + -s.i.m.s./F.t.m.s. with cooled liquid matrices and solid samples, laser desorption/F.t.m.s. and accurate mass measurements taken under each of these modes of operation.

Autoionization and the photoelectron spectra of oxygen

Abstract The photoelectron spectra of oxygen between 800 and 850 A have been recorded to probe the Rydberg series that converges to the a4Πu state of O2. These data were coupled with the theoretical work of Smith (see A. L. Smith, J. Quant. Spectrosc. Radiat. Transfer, 10 (1970) 1129) and demonstrate that the approach of Smith gives satisfactory calculated photoelectron peak intensities compared to the experimental ones in the presence of autoionization. Application of the calculated and experimental photoelectron spectra indicate that the v = 0 level of this Rydberg series should be 860.7 A instead of 853.2 A as previously assigned. At 736 A Smiths theory cannot be used to predict the correct peak intensities, because of an overlapping of autoionization levels at this energy.

The importance of the asymmetry parameter for interpreting photoelectron spectral intensities

Abstract The importance of the asymmetry paramter β on the observed photoelectron band intensities is illustrated by comparing the spectra of benzene obtained using polarized and unpolarized photons. This method is also used to give preliminary values for the asymmetry parameter of benzene at 740 A. The energy dependence of β follows the shape of that predicted by Lohr for π and σ orbitals in ethylene.

Laser desorption/fourier transform mass spectral analysis of various conducting polymers

Abstract Laser desorption/Fourier transform mass spectrometry provides very detailed characterization of conjugated aromatic ‘conducting’ polymers that cannot be obtained by other currently available techniques. The technique shows that many of the synthetic routes to these materials yield complex mixtures of dissimilar oligomers. Thus, it is not appropriate at present to attribute electrical conductivities to distinct, individual polymers. The intent of this paper is to present an introductory description of this analytical technique and to give examples of the experimental results that can be expected with intractable aromatic polymers which become electrically conductive upon doping.

Laser Mass Spectral Investigations of Rubber Compound Surface Species

Abstract Laser desorption mass spectrometry has proven a uniquely useful technique for the direct characterization of rubber-compound surface species. Mass spectra were obtained for intact molecular ions (M+) of organic chemical rubber additives such as the aromatic processing oil, and the aromatic antiozonant and antioxidants incorporated to protect the rubber. Molecular-weight information from the molecular ions and structural information from the fragmentation ions could be obtained without interference from the fragmentation peaks of the rubber backbone. Rubber compounding ingredients were also characterized by LDMS techniques. Differences in the structure of two carbon blacks were apparent, based upon the relative intensities of the various peaks present such as the significantly higher m/z 26 peak thought to be due to CN− compared to the m/z 24 peak thought to be due to C2−, and the peaks resulting from the presence of hydrogen atom(s) on the carbon clusters for the high NSA and DBPA black. Laser an...

Conductive Polymers and Carbon Clusters: Analysis of Chemical Composition by Nuclear Magnetic Resonance and Laser Desorption/Fourier Transform Mass Spectrometries

Abstract The electrical conductivity of aromatic polymers has become a topic of intense interest in recent years. Benzenoid and heterocyclic aromatic polymers [1–14] and polymers with nonaromatic heteroatoms in the backbone [15–27] (such as ideal structures 1–3, respectively) have been investigated. Not surprisingly, the electrical conductivities of different polymers are different. However, there also is much variation in the observed conductivities of individual samples of each polymer. Depending on the route of synthesis, extent of halogenation, identity and concentration of dopant, level of contaminants, and degree of crystallinity, observed conductivities can vary by as much as 6 orders of magnitude (e.g., Refs. 7, 13, 28, 29, and references therein). Clearly, analytical techniques that provide complete structural characterization of these polymers are needed in order to understand fully the structural properties that underlie their electrical conductivities.