Proton tunneling in the S-1 state of jet-cooled tropolone-(N-2)(n) (n = 1, 2) and tropolone-(CO)(1) van der Weals complexes is investigated by measuring the hole-burning and fluorescence excitation spectra in the S-1-S-0 region. The hole-burning spectra enabled us to separate three overlapping absorption systems due to transitions between low-wavenumber and high-wavenumber tunneling doublet components of tropolone-(N-2)(1) and those of tropolone-(N-2)(2). The 0-0 tunneling doublet splitting of tropolone-(N-2)(1) has been confirmed to be 9.7 cm(-1). It has been suggested that the magnitude of the tunneling splitting depends on the excited intermolecular vibrational level. In addition to the sandwich isomer I for tropolone-(N-2)(2) observed previously, a second isomer [II] has been identified. A much smaller microscopic red shift (-57.9 cm(-1)) than the corresponding value (-129.0 cm(-1)) for isomer I indicates that two N-2 molecules are on the same side of the tropolone ring in isomer Il. No tunneling splitting has been observed for tropolone-(N-2)(2)[II]. The hole-burning spectrum of tropolone-(CO)(1) indicates that only one species is observed in the excitation spectrum, although the existence of two isomers was reported previously (Chem. Phys. 1996, 213, 397). The vibronic bands of tropolone-(CO)(1) show no tunneling splitting. The intensity of the origin band of tropolone-(CO)(1) is considerably weaker than vibronic bands, suggesting that the equilibrium structure in the S-1 state is substantially different from that in the S-0 state. The decreases in the tunneling splittings of tropolone-(N-2)(n) (n = 1, 2) and tropolone-(CO)(1) are attributed to the coupling of the intermolecular vibrations with intramolecular vibrations, which may significantly increase the height of the potential energy barrier and distort the potential energy surface in the S-1 state, leading to the decreased tunneling splitting. This coupling is very strong when the adduct is bonded close to the O ... H-O moiety.