The isotope-ratio-enhancement calculations for <sup>138</sup>La are carried out using spectral-simulation (SS) and density-matrix (DM) methods for the 5d6s<sup>2</sup> <sup>2</sup>D<sub>3/2</sub>−5d6s6p <sup>4</sup>F<sub>3/2</sub><sup>0</sup> (753.9-nm) transition that was considered by Young and Shaw [J. Opt. Soc. Am. B <b>12</b>, 1398–1402 (1995)] a first-step transition in their diode-laser-initiated, resonance-ionization mass spectrometry experiments. The results from the two methods are compared with each other and with the reported experimental result. The SS result is noted to be more sensitive to the residual Doppler width but less sensitive to the laser linewidth than the DM result. It is further noted that under exact correspondence with experimental conditions, the DM result is in much better agreement with the experimental result obtained by Young and Shaw in their two-color resonant, three-photon photoionization of La by use of a narrowband, cw diode laser for the first-step excitation and a broadband, pulsed dye laser for further excitation and ionization.
© 2004 Optical Society of America
G. P. Gupta, A. K. Pulhani, and B. M. Suri, "Comparison of 138La:139La-isotope-ratio-enhancement calculations by use of spectral-simulation and density-matrix methods," J. Opt. Soc. Am. B 21, 436-441 (2004)