The relative intensities of the lines in 26 of the stronger multiplets of the spectrum of normal titanium, Ti I, and in 8 of the stronger multiplets due to the singly ionized atom, Ti II, were measured by a general method of photographic photometry which is described in detail. In Ti , 58% of the multiplets were found to obey the intensity formulas to well within 5%, while in the 42% of abnormal multiplets, 71% of the lines were found normal, with 16% abnormally weak and 13% abnormally strong. In Ti II, 62% of the multiplets measured were normal, while of the abnormal 38%, 61% of the lines were normal, with 21% abnormally weak and 18% abnormally strong. Of all the lines measured, 86% appeared normal in intensity, while 7.6% were too weak and 6.4% were too strong. The departures from the predicted intensities are often fairly large, generally being of the order of 10% to 40%. No definite correlation was found between intensity abnormalities and depatures from Lande’s interval rule or the normal Zeeman patterns.
GEORGE R. HARRISON, "INTENSITY RELATIONS IN THE SPECTRA OF TITANIUM," J. Opt. Soc. Am. 17, 389-416 (1928)