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$\sb2$Cl. 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.
| Identifer | oai:union.ndltd.org:RICE/oai:scholarship.rice.edu:1911/16392 |
| Date | January 1990 |
| Creators | Spence, James Hunter |
| Contributors | Curl, Robert F., Jr. |
| Source Sets | Rice University |
| Language | English |
| Detected Language | English |
| Type | Thesis, Text |
| Format | 265 p., application/pdf |
Page generated in 0.0019 seconds