D. Henseler et al., Intermolecular vibrations of 1-naphthol center dot NH3 and d(3)-1-naphthol-ND3 in the S-0 and S-1 states, J CHEM PHYS, 115(9), 2001, pp. 4055-4069
Hydrogen-bonded complexes of the photoacid 1-naphthol with NH3 and ND3 were
investigated by resonant two-photon ionization, spectral hole burning, and
fluorescence spectroscopies. Although the intermolecular vibrations are we
ak in both absorption and emission, with typical Franck-Condon factors <2%
relative to the electronic origin, all six intermolecular modes were identi
fied, namely the hydrogen bond stretch <sigma>, the ammonia torsion tau, tw
o in-plane wags beta (1) and beta (2), and two out-of-plane rocking motions
rho (1) and rho (2). Several ammonia torsional excitations were observed.
with spacings in good agreement with the S-0- and S-1 state effective torsi
onal barriers derived by Humphrey and Pratt [J. Chem. Phys. 104, 8332 (1996
)]. The beta (1), beta (2), and rho (2) vibrational excitations exhibit lar
ge (2-8 cm(-1)) torsional splittings, which indicate strong anharmonic coup
ling with the ammonia internal rotation. The observed Franck-Condon factors
of the intermolecular stretching vibration imply a contraction of the O-H
. . .N hydrogen bond by approximate to0.01 Angstrom upon S-1<--S-0 excitati
on, (C) 2001 American Institute of Physics.