Line shapes in high-resolution triple-resonance ionization spectroscopy hav
e been calculated and compared with experimental measurements on the 4s(2)
S-1(0)-->4s4p P-1(1)-->4s4d(1)D(2)-->4snf(1)F(3)-->Ca+ system of calcium. C
alculations based on the density matrix formalism integrated the fundamenta
l equations over experimental atomic angular and velocity distributions and
laser intensity profiles. The measurements reveal and confirm all predicte
d structures arising from the complex coupling of four atomic states with t
hree laser fields and the Doppler distribution of the atomic ensemble. Effe
cts of different laser beam geometries on the line shapes have been investi
gated. The agreement between calculated and experimental spectra is general
ly good over a dynamic range of 10 orders of magnitude. Thus these calculat
ions can accurately predict optical isotopic selectivity in multistep reson
ance ionization, with a value of S-opt similar to 10(10) expected for detec
tion of the ultratrace isotope Ca-41. (C) 2000 Optical Society of America.
OCIS codes: 300.6210, 300.6320, 300.6350, 300.6300, 300.6410.