COMPETITIVE SOLVATION OF NH3 AND H2O BY A PHENOL ION STUDIED BY LIQUID BEAM - MULTIPHOTON IONIZATION - MASS-SPECTROMETRY

Phenol in an aqueous ammonia solution was introduced into a vacuum as a continuous liquid flow (liquid beam) and was irradiated with a laser beam of 272 nm. Ions produced by two-photon ionization in the liquid beam and ejected from it were analyzed by a time-of-flight mass spectr ometer. The mass spectrum assignable to C6H5OH+ (H2O)(n) (NH3)(m), H3O + and NH4+ shows that a phenol ion produced by two-photon ionization o r a protonated ion produced by proton transfer from the phenol ion is ejected with several solvent molecules from the liquid surface, and th e nascent cluster ion decays by unimolecular dissociation before detec tion. The amount of NH3 in the nascent cluster ion at different NH3 mo le fractions is evaluated from that of the ions detected by taking its unimolecular dissociation into consideration. The results show that t he phenol ion solvates NH3 more favorably than H2O in the solution. (C ) 1997 Published by Elsevier Science B.V.