Coherent phase control of the photoexcitation of CH3I clusters was achieved by means of quantum mechanical interference between 1- and 3-photon transitions. Fundamental and frequency-tripled outputs of a visible laser (600.4-603.4 nm) were used to excite the CH3I clusters, and the resonance enhanced multiphoton ionization spectra with time-of-flight mass detection were measured. The CH3I+, CH3+, I+, and (CH3I)CH3+ signals observed in the mass spectrum exhibited the effects of phase modulation. All the modulations of these ion signals were in phase. This result indicates that the molecular phase was not affected by solvation in the clusters, (C) 2003 Elsevier B.V. All rights reserved.