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Fluorescence excitation, dispersed fluorescence, and population labeling spectra of six isotopes of 5-aminotropolone $(-OH/-NH2,-OH/-NHD,-OH/-ND2,-OD/NH2,-OD/-NHD$, and $-OD/-ND2$) are reported. A primary purpose of this study is to investigate the effect of the strong electron donation of the amino group on the intramolecular proton tunneling. Single vibronic level tunneling splittings in the $S0-S1$ transition of the supersonic-jet cooled molecules are used to probe these effects. Amino substitution produces a modest increase in the origin tunneling splitting, but has a more pronounced effect on the $260n$ progression involving a low-frequency out-of-plane vibration of the molecule. This progression, which dominates the spectrum of tropolone itself, is much reduced in intensity in 5-aminotropolone. At the same time, the excited state frequency of $v26$ is increased by almost a factor of two relative to tropolone. Both features point to a stiffening of the pseudo-aromatic ring induced by the amino group. Accompanying these changes is a much reduced sensitivity of the tunneling splitting to $Q26$ excitation. Similar data on 5-hydroxytropolone, involving a strong electron withdrawing substituent, will also be presented for comparison.[FIGURE]