The ring-puckering and ring-flapping vibrations of phthalan in its S-1(pi,pi*) electronic excited state have been studied using fluorescence excitation spectroscopy of jet-cooled molecules, dispersed fluorescence spectroscopy, and ultraviolet absorption spectroscopy. This electronic state has A(1) symmetry resulting from a B-2--> B-2 orbital transition. Thus type A absorption bands result from A(1)--> A(1) and B-2--> B-2 transitions to the S-1 vibronic levels. The ring-puckering levels for the S-1(pi,pi*) electronic state were determined for both the flapping ground (v(F)=0) and excited states (v(F)=1) and these were used to calculate both one- and two-dimensional potential energy surfaces which fit the observed spectra. In the S-1(pi,pi*) state phthalan was found to be planar and more rigid than in the ground state in terms of the puckering coordinate. However, the molecule is less rigid along the flapping coordinate. This study shows how several types of spectroscopy and computations must be used in conjunction with each other to attain a comprehensive analysis of the electronic excited state. (C) 2000 American Institute of Physics. [S0021-9606(00)00515-8].