A sodium iodide (NaI) solution in ethanol was introduced into a vacuum as a
continuous liquid flow (liquid beam) and was irradiated with an ultraviole
t laser beam. Ions ejected into the vacuum were mass-analyzed by a time-of-
flight mass spectrometer. The mass spectra show that Na+(EtOH)(m) (m = 0-6)
and Na+(NaI)(n)-(EtOH)(m) (n = 1-7) are ejected from the liquid beam. The
results are interpreted as that these cluster ions are produced by unimolec
ular dissociation of nascent cluster ions composed of Na+ solvated with eth
anol and/or (NaI)(n), which are born on the liquid surface. The dependence
of the ion intensities on the NaI concentration indicates formation of NaI
aggregates on the liquid beam surface in the entire NaI concentration range
studied.