Sharp series

The sharp series members are all simple doublets which all show the same splitting, namely, that of the i P n and states. 

Figure 12.7 Electronic transitions giving rise to the emission spectrum of sodium in the visible, as listed in Table 12.1. The principal series consists of transitions from the 3s level to 3p or a higher p orbital the sharp series from 3p to 4s or a higher s orbital diffuse from 3p to 3d or above and the fundamental from 3d to 4/or higher. The terms below the lines [(R/(3-1.37)2, etc.] are the quantum defect corrections referred to in Section 10.4.

Petrikaln (Ref 7) photographed the spectra of Zn(N3)a and other azides. With the azides of Ca, Sr and Ba, not only triplet system lines but also those of the singlet system were emitted. Zn(N3)a emitted only triplet system lines of the diffuse and sharp series. In addn the oxide bands were present in all the spectra. Kahovec Kohlrausch (Ref 13) detd the Raman spectra of basic zinc azide crysts. 

In Eq. (1.4) the + sign and constant n describe a sharp series of s states and the minus sign and a constant m describe a principal series of p states. If we consider the special case ds = dp = 0 and m = 2 we arrive at Balmer s formula for the H transitions from n=2. 

From the early spectroscopic work it is possible to construct an energy level diagram for Na, as shown in Fig. 1.1. From this figure it is apparent that the difference in the principal and sharp series limits is the wavenumber of the 3s-3p transition. It is also apparent that the Rydberg states, states of high principal quantum number n, lie close to the series limit. 

For both PF2/6 and PF8 the aforementioned main chain characteristics are essentially identical and so any pronounced differences are likely to originate in secondary structural characteristics of the functionalizing side chains. PF8 studies by Bradley and coworkers [16] first identified the unusual spectroscopic emission band now conventionally referred to as the phase . The hallmark signature of this peculiar chain structure is a relatively sharp series of emission bands red shifted some lOOmeV from those seen when the polymer is prepared in a glassy state, tt-Conjugated polymers have strong electron-phonon coupling and so, in addition to the it-it emission, there is a manifold of vibronic overtones spaced approximately 180 meV apart and red-shifted from the dominant n-n emission band. 

There are therefore three terms for every azimuthal quantum number, and the term scheme of orthohelium is a triplet system. Here also, however, as in the doublet spectra discussed above (p. 136), the 5-terms are single in fact, I = 0 for these, so that j can only be equal to s, i.e. to 1. In the alkaline earths (Be, Mg, Ca, Sr, Ba), which like helium have two external electrons, the triplet character can be easily observed in the spectrum. In helium, however, a special feature occurs it possesses practically a doublet spectrum, since the and Pg terms nearly coincide. As an example of this, we take the st line of the sharp series, which corresponds to the transition from to 2P. Exact measurements by Houston have shown that this line consists of three components ... 

Fig. 8.30. Case of very broad perturbers interacting with a sharp series = —0.05, X2 = —0.06, and = 106 (after J.-P. Connerade [444]).

In the triplet spectrum, the series lie in the longer wavelength region, ranging from the visible to the infrared. Each line in the triplet spectrum consists of a number of closely spaced lines the separation between these lines increases rapidly as the atomic number increases in the two-electron species He, Be, Mg, Ca, Sr, Ba, Zn, Cd, Hg. Consider the first line in the sharp series in calcium, corresponding to the transition from 5 S to 4 P. Since the 5 S level is a single level while the 4 P level is split into three levels, the line consists of three closely spaced lines A = 610.272 nm, 612.222 nm, and 616.218 nm. The transition from 4 D to 4 P yields a group of six closely spaced lines. In contrast to the alkali metal case in which the levels were not split, in calcium the levels are split into three levels. If each level of could combine with each level of P, nine lines would be expected. In fact, the selection rule, AJ = 0, + 1, rules out three of these possibilities so that only six lines appear. This situation is illustrated in Fig. 24.11. The transitions J = 2 -> 0, 3 - 1, and 3 -> 0 are forbidden. 

The sharp series of bands beginning at 124 nm in H2O, and extending to shorter wavelengths, have long been associated with Rydberg transitions populatii linear, bound excited states" The first sharp band in the absorption spectrum of H2O, which occurs at 1. 1 nm has been assigned to the transition bx 3pa (C Ri -f-X) The band has a clearly defined rotational... 

In fact the Heath Sharp series is identical in form and origin to the classical progression in ionisation energies for the p-block elements (B to Ne and A1 to Ar). This arises through the strict isomorphism of pn and t2n configurations. It is a remarkable relationship it spans light element atoms vs molecular metal complexes and it spans gas phase spectroscopic data vs equilibrium (electrochemical) measurements in solution. 

Figure 2.2 Schematic emission spectra of H, K, and Hg atoms. These are plotted versus the line frequencies v = 1/A in units of cm V where the A are the emission wavelengths in vacuum. Only the strongest emission lines are included, and relative line intensities are not shown. Line headers for H and K denote series of lines resulting from transitions terminating at a common lower level. Line headers are omitted for the Pfund series in H (which appears at extreme left) and for the sharp series in K, which closely overlaps the diffuse series.

On the other hand, the vapor-phase pyrolyzates are very different (see Figure 14.20). The sharp series of bands near 2800 cm is due to HCl and clearly come from the decomposition of the chlorinated polymer. 

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