# AUTOIONIZING RYDBERG STATES OF CaCl

Please use this identifier to cite or link to this item: http://hdl.handle.net/1811/13351

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 Title: AUTOIONIZING RYDBERG STATES OF CaCl Creators: Gittins, C.; Harris, N.; Field, R. W. Issue Date: 1994 Publisher: Ohio State University Abstract: Rotationally resolved, vibrational autoionization detected, optical-UV double resonance spectra of CaCl have been observed above the v=0 ionization threshold. The observed Rydberg states have $n^{*} >15$ and v=1. The experiment is a variation on traditional optical-optical double resonance (OODR) experiments in that the signal is produced by autoionization, rather than by UV fluorescence or a fluorescence dip. All spectra were recorded using $A^{2}\Pi_{3/2}-X^{2}\Sigma^{+}_{1/2} (0.0)$ PUMP $transitions^{1,2}$. The Rydberg-$A^{2}\Pi_{3/2} (1,0)$ transitions are in the near UV. Vibrational autoionization is found to be much more efficient than direct ionization from $A^{2}\Pi_{3/2}, v=0$ to $(CaCl)^{+}, v^{+}=0$. As the most useful $Ca^{35}Cl$ and $Ca^{37}Cl$ PUMP transitions are often coincident, double resonance does not always discriminate between the two isotopic species. The isotopomers are distinguished of Rydberg-$A^{2}\Pi_{3/2}$ transitions. Several series have been followed from $n^{*}-15$ through 43. The $n^{*}=16$ supercomplex has been analyzed in detail. The observed spectra cannot be explained in terms of pure-l $states^{3,4}$. An abrupt decrease in the density of observed transitions occurs near $n^{*}=25$. This effect is believed to be a result of the operating of a predissociation channel. The CaCl ionization potential has been (spectroscopically) determined to be 6.012(1) eV. The $(CaCl)^{+}$ rotational constant and vibrational frequency will also be reported. URI: http://hdl.handle.net/1811/13351 Other Identifiers: 1994-WG-03