We study the absorption spectrum of a V-type three-level atom when the lase
r beam interacts only with one of its two transitions. With the presence of
vacuum-induced quantum interference, the absorption spectrum shows some ne
w interesting features, which include ultranarrow absorption line, transpar
ency, and a reverse-saturated absorption that is characterized by a larger
absorption with increasing laser intensity. (C) 2001 Elsevier Science B.V.
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