Strontium line spectrum

Figure 7.7 The line spectra of several elements. A, A sample of gaseous H2 is dissociated into atoms and excited by an electric discharge. The emitted light passes through a slit and a prism, which disperses the light into individual wavelengths. The line spectrum of atomic H is shown (top). B, The continuous spectrum of white light is compared with the line spectra of mercury and strontium. Note that each line spectrum is different from the others.

The spectroscope revealed the presence of sodium, potassium and some lithium in the filtrate. In addition we observed two remarkable blue lines, very dose together. One of them was in the part of the spectrum where a well-known strontium line is situated. No element, earlier identified, has a pair of lines in this part of the spectrum. Our condusion is that we have discovered a new alkali metal and we propose the name cesium for this new element. 

In general, excited atoms emit spectral lines, i.e. the radiation lies in very narrow wavelength ranges of width 10 to 10 nm. In practice, atomic resonance lines from species, such as strontium in a red star, contribute little to the visual effect since the emission falls in the short wavelength part of the spectrum (this line may be observed in a Bunsen burner flame at 461 nm). 

An excess of chlorine, introduced into reaction (8.7) causes a shift to the left and an improvement in the flame saturation of strontium monochloride. Table 8.3 shows the main emission bands/lines for a red star. Figure 8.8 shows the radiant spectrum of a typical red star. 

Fox Talbot (24), an English scientist, found in 1834 that, with the aid of a prism, he could distinguish lithium from strontium, even though the salts of both give red flames (4, 26, 32). He stated that the dark lines previously observed by Sir David Brewster (33) in the spectrum of light which had passed through vapors of nitrous acid were caused by absorption of light (5,25). 

An interpretation of the absorption spectrum in the low-excitation phase has been made by Williams (1987), based on line identifications of scandium, strontium,... 

Line spectra occur when the radiating species are individual atomic particles that are well separated, as in a gas. The individual particles in a gaseous medium behave independently of one another, and the spectrum in most media consists of a series of sharp fines with widths of 10 to 10 - A (10 to 10 nm). In Figure 24-19, fines for sodium, potassium, strontium, calcium, and magnesium are identified. 

The Englishman Fox Talbot showed in 1834 that, with a prism, it was possible to distinguish between Hthium and strontium, although both emit red Hght when they are heated. The strontium radiation has many red lines and an orange and a blue. The spectrum of Hthium contained only one red line. 

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