Collective Excitation in the Ba I Absorption Spectrum

James Floyd Kelly

The uv absorption spectrum of Ba vapor is studied, noting its dependence on both vapor density and the intensity of illumination. Wavelength positions of the weak absorption lines, which appear adjacent to the $6snp ^{1}P_{1}^{o}$ principal series for $n\ensuremath{\gtrsim}35$, have been identified as the $6{s}^{2}^{1}S_{0}$ to $6sns^{1}S_{0}$ and $6snd^{1}D_{2}$ even-parity transitions. Experimental evidence is presented to support the interpretation of these transitions as collision-induced phenomena.

F. J. Kok

G. V. Gadiyak, D. A. Kirzhnits, Yu. E. Lozovik

Robert F. O’Connell

The Zeeman effect in the Ba I absorption spectrum has been observed by Garton and Tomkins. One striking feature of the spectrum they obtained is the existence of a sequence of a lines, extending across the zero-field series limit into the continuum, with a regular spacing of about 1 .Shw, where w is the cyclotron frequency. A semiclassical explanation is given for this result. Subject headings: atomic processes - Zeeman effect

Peter Moroshkin, Kimitoshi Kōno

We present an experimental and theoretical study of the emission and absorption spectra of the ${\mathrm{Ba}}^{+}$ ions and ${\mathrm{Ba}}^{+*}\mathrm{He}$ excimer quasimolecules in the cryogenic Ba-He plasma. We observe several spectral features in the emission spectrum, which we assign to the electronic transitions between bound states of the excimer correlating to the $6{\phantom{\rule{0.16em}{0ex}}}^{2}{P}_{3/2}$ and $5{\phantom{\rule{0.16em}{0ex}}}^{2}{D}_{3/2,5/2}$ states of ${\mathrm{Ba}}^{+}$. The resulting ${\mathrm{Ba}}^{+}(5{\phantom{\rule{0.16em}{0ex}}}^{2}{D}_{J})\text{He}$ is a metastable electronically excited complex with orbital angular momentum $L=2$, thus expanding the family of known metal-helium quasimolecules. It might be suitable for high-resolution spectroscopic studies and for the search for new polyatomic exciplex structures.

G. V. Gadiyak, D. A. Kirzhnits, Yu. E. Lozovik