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Continuing our study of internal motions of isoelectronic species attached to the naphthalene chromophore, we report here the observation and analysis of the $S1\to S0$ fluorescence excitation spectra of 1- and 2-aminonaphthalene as well as many isotopically substituted derivatives at a resolution of - 10 MHz in the UV. Deuterium has been used to label both the amino hydrogen positions and selected ring hydrogen positions. The rotational constants obtained from analyses of these spectra, in conjunction with Kraitchman's equations, has allowed us to define geometric features of the protonated molecule in both states. We also find the $000$ band of 1-aminonaphthalene (1AN) to be primarily b-axis polarized, contrary to earlier obervations on 1AN and related species.2 We also obtain information about the magnitudes of the barriers to inversion of the amino group in both states. These results will be summarized and discussed in the framework of molecular orbital theory. A brief overview of the software developed to record and analyze the high resolution spectra of large polyatomic molecules also will be given.