Barium, atomic spectrum

Barium atoms have a particular transition that emits light of frequency 5.41 X 10 " Hz. (Hz is the abbreviation for hertz, which is equivalent to the unit /s, or s ) Is this light in the visible spectrum If so, what is the color of the light (See Figure 7.5.)... 

After the Curies, with the assistance of M. G. Bemont, had carried out many laborious fractionations of barium chloride, they found that the most insoluble fractions were the most radioactive. In the course of her experiments Mme. Curie had learned that radioactivity is an atomic property depending solely on the quantity of active element present." For this reason the presence of another active element was suspected, and the radioactive barium chloride was therefore submitted to M. Demarcay for spectroscopic examination. He detected a new line in the ultraviolet region of the spectrum, and certain other lines, all of which were most distinct in the most radioactive preparations, and, as fractionation proceeded, the barium lines became fainter and fainter (23, 28, 52). 

In most laser studies of optical isotope shifts the crossed, laser-atomic beam method is used to avoid Doppler-broadening. In some cases short-lived radioactive isotopes are detected directly on-line, in others, by irradiating a target which is subsequently heated to form the source of an atomic beam. Figure 7 shows a spectrum obtained some years ago in Oxford on the resonance line of barium at 554 nm S] ... 

---