Journal of Chemical Physics, Vol.115, No.1, 270-276, 2001
Experimental determination of phenol (CH3F)(1) complex binding energies in the S-0, S-1, and I-0 states and comparison with ab initio calculations
Weakly bound complexes of phenol (Ph) and fluoromethane (CH3F) formed in a supersonic expansion have been identified by one-and two-color mass-resolved and hole burning spectroscopies. Only one isomer has been observed for the 1:1 complex. Threshold fragmentation has been employed to determine the binding energies of the complex in its ground, S-0, and first electronic, S-1, states, as well as in the ion ground state, I-0, yielding the following results: D-0(S-0)=1540 +/- 50 cm(-1), D-0(S-1)=1713 +/- 50 cm(-1), and D-0(I-0)=3932 +/- 50 cm(-1), respectively. In a complementary study, calculations on the complex geometries and binding energies were conducted at the B3LYP/6-31+G* and the MP2/6-31+G* levels. It has been shown that the binding energies computed at the MP2/6-31+G* level are in excellent agreement with the experimental values, whilst those calculated at the B3LYP/6-31+G* level underestimate them by nearly 30%, probably due to the poor description of the dispersion forces.