Subband intensity anomalies

The subband intensity anomaly arises from AS = 0, A Cl = 0, ff / 0, E+ E-spin-orbit perturbations combined with the opposite behavior of the phase factors for E+ — IIfi=1 versus E — IIn=i s transitions (Section 6.3.2). The nominal E+ and E eigenstates are... 

A special class of intensity anomaly arises from E+ E perturbations. Ren-horn (1980) has shown that interference between two transition moments could account for the anomalous (2E — 2n3y2) / (2 — 2Ifi/2) subband intensity ratios observed by Appleblad, et al, (1981) in a CuO 2E — X2II transition at 767 nm. An unperturbed 2E —> 2II transition should have approximately equal intensity E — n3/2 and E — II1/2 subbands. The fi // interference effects discussed in Section 6.3.2 only affect R/P intensity ratios within a subband without changing the total subband intensity. 

M M-L interference effects in a 3II 1S transition appear as anomalies in the ratios of R and P branch intensities, primarily in the 3IIi — 1E+ and 3IIo — 1E+ subbands. The Q lines can never be affected because the fi mechanism cannot contribute to their intensity. If /i[ > ]/ij ], the R/P anomalies will be most pronounced in the weaker (3IIi — 1E+) subband as is observed by Lee, et al., (2000) fortheRb2 23IIU-X1E+ transition. If /r < m , the anomalies will appear in the weak (3IIo — 1E+) subband. At some J value, either the P(J + 1) or the R(J — 1) line in the weaker subband will vanish, having transferred all of its transition probability to its same-subband partner. 

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