The rare gas alkali ionic molecules are established as a new class of ionic excimers which emit in the vacuum ultraviolet (VUV) regime of the electromagnetic spectrum. Temporal and spectral characteristics of these species with (XeRb)$\sp{+}$ at 164 nm and (XeCs)$\sp{+}$ at 160 nm have been investigated by soft x-ray excitation in a laser-produced plasma and by high energy pulsed electron beam pumping in this work. Soft x-ray pumping of XeF(B $\to$ X) and (XeRb)$\sp{+}$ yielded the first observation of excimer molecules formed by reactive kinetics in a laser-produced plasma.
The spectrum of (XeRb)$\sp{+}$ was observed. The spectral structure could be assigned to 3 dipole allowed transitions originating from the 0$\sp{+}$(II), 1(II), 1(I) upper states ending in the 0$\sp{+}$(I) ground state. A kinetic study of electron beam pumped mixtures of Ar/Xe/Rb and Ar/Xe/Cs was performed. The observed temporal decays of (XeRb)$\sp{+}$ and (XeCs)$\sp{+}$ were analyzed. The results suggest that electron deactivation is surprisingly not a dominant quenching process for rare gas alkali ions.
The radiative lifetimes are 150 $\pm$ 50 ns for (XeCs)$\sp+$ and 250 $\pm$ 50 ns for (XeRb)$\sp+$. In addition several quenching rate constants were extracted from the experimental results. These rate constants and lifetimes were incorporated into a kinetic model for these species. This kinetic model reproduced the experimental observations well providing the electron quenching rate coefficient is kept to a maximum of 5 $\times$ 10$\sp{-9}$ cm$\sp3$s$\sp{-1}$. Estimates for the upper state densities were computed using this model to be $\sim$4 $\times$ 10$\sp{15}$ cm$\sp{-3}$ for (XeCs)$\sp+$ and 2 $\times$ 10$\sp{15}$ cm$\sp{-3}$ for (XeRb)$\sp+$. Including absorption due to the photoionization of the alkali atoms, the net gain coefficients are computed to be on the order of 10$\sp{-2}$ cm$\sp{-1}$. Therefore the rare gas alkali ionic excimers appear to be a promising class of candidates as storage media for VUV lasers.
| Identifer | oai:union.ndltd.org:RICE/oai:scholarship.rice.edu:1911/16370 |
| Date | January 1990 |
| Creators | Millar, Pamela S. |
| Contributors | Sauerbrey, R. |
| Source Sets | Rice University |
| Language | English |
| Detected Language | English |
| Type | Thesis, Text |
| Format | 128 p., application/pdf |
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