Transition region spectroscopy of dialkali halides: Sodium(2)chloride and sodium(2) + atomic fluorine going to sodium fluoride + sodium

Abstract

Molecular beam chemiluminescence from Na\sb2 + F \to NaF + Na\sp\* was dispersed and measured with a fast spectrograph. Attention was given to emission wavelengths at and around 388.5 and 342.8 nm, which correspond to the electric dipole forbidden atomic transitions Na 4s \to 3s and 3d \to 3s, respectively. It was hoped that the nascent products NaF and Na\sp\* would interact such that these normally dis-allowed transitions could be observed, thereby constituting a direct glimpse of the three atom system late in the reaction event. A small emission peak was observed at the 3d \to 3s transition wavelength, but its weak intensity could be explained by electric quadrupole radiation of the free atom rather than a reaction-induced breaking of dipole selection rules. No structured emission was observed at the 4s \to 3s wavelength, although interference from Na\sb2\sp\* may be obscuring an otherwise observable peak. In a second experiment, two lines of an argon ion laser are crossed with a single Na/NaCl beam in an effort to observe resolved laser-induced fluorescence of the stable molecule Na\sb2Cl. The copious emission from Na\sb2\sp\* precluded any definitive identification of fluorescence from the target molecule. Finally, a detailed description is given of the f/2 spectrograph that was developed in this laboratory. The instrument observes a 100 nm wavelength region simultaneously, images atomic lines to a full-width-half-maximum (fwhm) of 2 nm, has a photocathode quantum efficiency of 3.1% at 800 nm, and exhibits only 36 counts per second dark current

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oaioai:scholarship.rice.e...Last time updated on 6/11/2012

This paper was published in DSpace at Rice University.

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