PROTON TUNNELING IN THE TROPOLONE-N-2 VAN-DER-WAALS COMPLEX

Proton tunneling splitting has been measured for the S-0 --> S-1 origi n band of the tropolone: N-2 van der Waals complex by recording its la ser-induced fluorescence excitation spectrum in a supersonic jet. A la rge decrease in the magnitude of the tunneling splitting, from 19.4 cm (-1) in bare tropolone to 6.0 cm(-1) in the 1:1 complex, has been obse rved, indicating that nitrogen perturbs the reaction coordinate by sig nificantly increasing the barrier height in the excited state. Strong coupling of the tunneling mode to the in-plane N-2 torsional mode is t he Likely source of this effect.