The mass distribution of neutral carbon clusters generated by a laser
vaporization of graphite in He was safely determined by a single photo
n (10.5 eV) ionization technique. The resulting mass distribution was
surprisingly different from those reported in previous articles. It wa
s found that the carbon clusters generated under a moderate laser flue
nce condition (0.1-1 J/cm(2)) consists of mostly even-numbered monocyc
lic rings with the cluster sizes of n = 10-18. The formation mechanism
of such neutral carbon clusters upon laser irradiation is discussed.
(C) 1997 American Institute of Physics.