ch39-p011

# ch39-p011 - 11. We can use the mc2 value for an electron...

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11. We can use the mc 2 value for an electron from Table 37-3 (511 × 10 3 eV) and hc = 1240 eV · nm by rewriting Eq. 39-4 as E nh mL c mc L n == 22 2 2 2 8 8 b g c h . (a) The first excited state is characterized by n = 2, and the third by n' = 4. Thus, () ( ) 2 3 1240eV nm 4 2 6.02eV 16 4 8 8 511 10 eV 0.250nm 72.2eV . hc En n mc L ∆= − = × = Now that the electron is in the n' = 4 level, it can “drop” to a lower level ( n'' ) in a variety of ways. Each of these drops is presumed to cause a photon to be emitted of wavelength λ= = ′ − ′′ hc EE mc L hc n n nn 8 ch c h . For example, for the transition n' = 4 to n'' = 3, the photon emitted would have wavelength × ⋅− = 8 511 10 0 250 1240 4 3 29 4 3 2 eV nm eV nm nm, c hb g b gc h . . and once it is then in level n'' = 3 it might fall to level n''' = 2 emitting another photon. Calculating in this way all the possible photons emitted during the de-excitation of this system, we obtain the following results:

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## This note was uploaded on 06/03/2011 for the course PHY 2049 taught by Professor Any during the Spring '08 term at University of Florida.

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ch39-p011 - 11. We can use the mc2 value for an electron...

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