Rotational structure in the Hopfield series of N2

• Published in: The Journal of chemical physics 1993-03, Vol.98 (6), p.4471-4477
• Main Authors: HUBER, K. P, STARK, G, ITO, K
• Format: Article
• Language: English
• Subjects: Atomic and molecular physics; Electronic structure of atoms, molecules and their ions: theory; Exact sciences and technology; Physics; Potential energy surfaces
• ISSN: 0021-9606; 1089-7690
• DOI: 10.1063/1.465006

The Hopfield Rydberg series of 14N2 have been reinvestigated both at room temperature under equilibrium conditions and at a rotational temperature of ∼20 K in supersonically expanding nitrogen. High-resolution absorption spectra of the preionizing resonances in the region from 143 000 to 151 100 cm−1 have been recorded photographically as well as photoelectrically using, respectively, the 10.6 m vuv spectrograph of the National Research Council in Ottawa, Canada, and the 6.65 m scanning spectrometer at the Photon Factory synchrotron facility in Tsukuba, Japan. The photoelectric measurements have been reduced to absolute photoabsorption cross sections. The rotationally cold spectra show strikingly regular patterns of absorption peaks and window resonances that are accounted for, semiquantitatively, by the calculated total ionization cross sections for the nonrotating molecule [M. Raoult et al., J. Phys. B 16, 4601 (1983), and unpublished work by H. Le Rouzo and M. Raoult, quoted by C. H. Greene and Ch. Jungen, in Adv. At. Mol. Phys. 21, 51 (1985)]. The complexity of the room temperature spectra is rotationally induced; it does not call for an interpretation in terms of strong interactions with an unidentified perturber state as suggested by Baig and Connerade [J. Phys. B 19, L605 (1986)].