The performance characteristics of a series of new excimer pumped ultraviolet dyes are presented. Chemical structure modifications which influence dye performance are discussed. An evaluation of several alternative solvents shows that p-dioxane remains the solvent of choice based on dye performance. The influence of the cover gas in the dye circulator was examined and results are presented to show how dye performance can greatly depend on this factor.

We report the performance of two new laser dyes, Pyrromethene 580 and 597, in a 10-Hz, Nd:YAG-pumped dye-laser system. These dyes demonstrate broader and more efficient tuning curves compared with those of Rhodamine 590 and 610. Pyrromethene 580 and 597 provide peak conversion efficiencies of 38% at 552 nm and 32% at 571 nm, respectively. Moreover, these new dyes provide conversion efficiencies of 31% near 572.5 nm, a wavelength used for fluorescence studies of NO. This enhanced efficiency should improve the signal-to-noise ratio in linear fluorescence [NO] measurements.

The spectroscopic and lasing characteristics of a series of 308 nm pumped p-oligophenylenes with five or more phenyl rings have been studied. Quantitative comparisons of the absorption spectra of these dyes with numerous other dyes in this class of compounds can be made by defining a parameter, theta, as the sum of the number of phenyl rings and the number of ring-bridges. Statistically good linear regressions result from the correlations of molar extinction with theta and from wavelength of absorbance with the reciprocal of theta. We find that these correlations provide good predictive information in deciding which dyes to attempt to synthesize for testing. The lasing characteristics of the dyes studied show that these dyes are amongst the best dyes in this class of dyes. Some of these dyes have exceptionally long lifetimes coupled with acceptable conversion efficiencies.

m ‐Chloroperbenzoic acid reactant: 52.5 g. (0.300 mole) of m ‐chlorobenzoyl chloride product: m ‐chloroperbenzoic acid

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