Atomic spectra excited state

To the extent that the electronic structure is describable in terms of independent atoms, the properties of inert-gas solids are easily understandable and not so interesting. There are, however, one or two points that should be made. The optical absorption spectra of isolated atoms consists of sharp lines that correspond to transitions of the atom to excited states, and to a continuous spectrum of absorption beginning at the ionization energy and continuing to higher energy. The experimental absorption spectra of inert-gas solids (Baldini, 1962) also show fairly sharp lines corresponding to transitions from the valence p states to excited s... 

The atomic absorption spectrum for Na is shown in Figure 10.19 and is typical of that found for most atoms. The most obvious feature of this spectrum is that it consists of a few, discrete absorption lines corresponding to transitions between the ground state (the 3s atomic orbital) and the 3p and 4p atomic orbitals. Absorption from excited states, such as that from the 3p atomic orbital to the 4s or 3d atomic orbital, which are included in the energy level diagram in Figure 10.18, are too weak to detect. Since the... 

Another feature of the spectrum shown in Figure 10.19 is the narrow width of the absorption lines, which is a consequence of the fixed difference in energy between the ground and excited states. Natural line widths for atomic absorption, which are governed by the uncertainty principle, are approximately 10 nm. Other contributions to broadening increase this line width to approximately 10 nm. 

In 1957, this team of brothers-in-law started working together on Townes s idea for an optical maser. They found atoms that they felt had the most potential, based on transitional probabilities and lifetimes. However, there was still one major problem In the visible light portion of the electromagnetic spectrum, atoms don t remain in an excited state as long as... 

Since an atom of a given element gives rise to a definite, characteristic line spectrum, it follows that there are different excitation states associated with different elements. The consequent emission spectra involve not only transitions from excited states to the ground state, e.g. E3 to E0, E2 to E0 (indicated by the full lines in Fig. 21.2), but also transisions such as E3 to E2, E3 to 1( etc. (indicated by the broken lines). Thus it follows that the emission spectrum of a given element may be quite complex. In theory it is also possible for absorption of radiation by already excited states to occur, e.g. E, to 2, E2 to E3, etc., but in practice the ratio of excited to ground state atoms is extremely small,... 

The Humphreys series is set of spectral lines in the emission spectrum of atomic hydrogen that ends in the fifth excited state. 

Not much is known about these processes, but they must be included to give a total picture. Emissions of Lyman and Balmer spectra of the H atom upon e-impact on hydrocarbons, H2, and H20, discussed in Sect. 4.3.2, fall in this category. Similarly, many of the excited states observed in dissociated radicals via electron impact on stable molecules (Polak and Slovetsky, 1976) also belong to this category. It is known from the dipole oscillator spectrum of H20 (Platzman, 1967) that most ionizations are accompanied by considerable excitation. Excitation transfer to the neighboring neutral molecule followed by fast dissociation cannot be ruled out. 

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