EVIDENCE FOR THE CYCLIC FORM OF PHENOL TRIMER - VIBRATIONAL SPECTROSCOPY OF THE OH STRETCHING VIBRATIONS OF JET-COOLED PHENOL DIMER AND TRIMER

The OH stretching vibrations of the phenol dimer and trimer prepared in supersonic jets have been observed by IR-W double-resonance and stimulated Raman-UV double-resonance spectroscopies. In the trimer, all the three OH stretching vibrations showed large red shifts from that of bare phenol. Evidence of the cyclic structure was obtained from an intensity alternation between IR and Raman spectra and by the measurement of the Raman depolarization ratios. In the dimer, it was found that the LR intensity of the OH stretching vibration of the proton-donating phenol is 4 times larger than that of the proton-accepting phenol.