Oscillator strengths of some higher Cs principal series lines

The oscillator strengths of the principal series doublet of Cs f 3/2 (6 2 S 1/2 -n 2 P 3/2 , 15<or=n<or=27) and f 1/2 (6 2 S 1/2 -n 2 P 1/2 , 15<or=n<or=21) have been measured in absorption using a high-resolution spectrometer. The oscillator strength ratio of the fine-structure components rho =f 3/2 /f 1/2 was found to increase monotonically with the principal quantum number n. From an extrapolation of the relevant Fano function a maximum in the ratio rho should not be expected for higher n.