Iodine spectrum emission

The caged pair 16 can lose the second C02 to yield a new pair 18 18 retains the net polarization of 16, which was emission for the CH2, but now acquires in addition a multiplet effect in the sense EjA for the CH2 group. The CH2 in the product phenylethane (19), group 4 in the spectrum, shows superposition of the net emission, E, and a multiplet effect in the predicted sense EjA. (The CH3 of this product is evidendy obscured by the CH3 of the ethyl benzoate.) Ethyl radicals that escape from the cage either react with iodine to give ethyl iodide, groups 3 (CH3) and 5 (CH2), which shows net polarization just opposite... 

In emission spectroscopy the molecule or atom itself serves as the somce of light with discrete frequencies to be analyzed. In some cases, such as Exp. 39, which deals with the emission spectrum of molecular iodine vapor, excitation by a monochromatic or nearly monochromatic laser or mercury lamp is utilized. For other cases, such as the emission from N2 molecules, electron excitation of nitrogen in a discharge tube provides an intense somce whose spectrum is analyzed to extract information about the electronic and vibrational levels. Such low-pressure (p < 10 Torr) line somces are available with many elements, and lamps containing Hg, Ne, Ar, Kr, and Xe are often used for calibration purposes. The Pen-Ray pencil-type lamp is especially convenient for the visible and... 

Continuous wave operation of COIL is facilitated by the hyperfine structure of the atom. Iodine has a nuclear spin of, so the P /2 and Pz/2 levels are split by hyperfine interactions. Figure 8 shows the allowed transitions between the hyperfine sublevels and a high resolution emission spectrum. The F = 3 — F" = 4 transition is most intense, and this is the laser line under normal conditions. Collisional relaxation between the hyperfine sub-levels of Pz 2 maintains the population inversion, while transfer between the Fi/2 levels extracts energy stored in the F = 2 level. Hence, if it is not sufficiently rapid, hyperfine relaxation can limit power extraction. 

The very different spectra of iodine obtained under continuum and discrete resonance-Raman conditions are illustrated in Fig. 11 for resonance with the B state, whose dissociation limit is 20,162 cm . In the case illustrated of discrete resonance-Raman scattering, Xl =514.5 nm, and specific re-emission results from an initial transition from the v" = 1 vibrational, J" = 99 rotational level of the X state to the v = 58, J = 100 level of the B state, i.e. the transition is 58 - l" R(99). Owing to the rotational selection rule for dipole radiation, AJ = 1, a pattern of doublets appears in the emission. Clearly, the continuum resonance-Raman spectrum of iodine (Xl = 488.0 nm) is very different from the discrete case spectrum. The structure, which arises from the 0,Q, and S branches of the multitude of vibration-rotation transitions occurring, can be analysed in terms of a Fortrat diagram, as done for gaseous bromine (67). 

Figure 3 Systematic variation in the energy of K and L fiuorescence emission iines with atomic number in the region 0-30 keV. The main sequence of K-iines for the eiements carbon to teiiurium is piotted, together with associated L-iine emissions (iron-teiiurium). Additionai L-iine emissions found in this region of the spectrum are piotted for convenience in two groups, iodine-iutetium and hafnium-uranium. Line heights correspond approximateiy to the reiative intensities of emission iines, and for ciarity, minor L-iine emissions have been omitted.

Figure 4. Auger electron spectrum, in the iodine emission region, of Pd(llO)-pseudohexagonal-I before (dashed curve) and after (solid curve) removal of approximately 10 monolayers of Pd(llO) surface atoms. These spectra correspond to the LEED patterns (B) and (C), respectively, in Figure 3. Incident beam energy = 2 keV beam current = 1 pA.

---