Upper spin-orbit states

X 10 cm molecule" s" is obtained, and discrepancies in the previously reported values are probably due to neglect of the reverse processes taking place.For the corresponding state in atomic fluorine, diode laser measurements of the absorption cross-section of the "Pi - transition at 404cm" yields a radiative lifetime of 660s for the upper spin-orbit state. ... 

This calculation of assumes that reaction is from the F( P3/2) ground state, and that the F( Pi/2) state, which is 1.15 kcal/mole higher in energy can be ignored. The observation (59) of Br( Pj /2) a product channel from the F + HBr reaction suggests that formation of the upper spin-orbit states can be important. The Br( P3 2) state may be formed from the reaction of the F(2pi/2) state, but further work is required to prove this. Two recent theoretical papers bear on this subject. Tully (73) predicted that Pi/2 only 0.14 as reactive as P3/2 300°K and... 

Rydberg state at about 68 000 cm-i, which was ionized into the upper spin-orbit state of the ion. For the spectrum given in Figure 4A, which was through the origin, the Av = 0 transition was most intense the total transition energy to this level is 75 066 2 cm"i, which is the adiabatic ionization energy (to the ion in... 

Guo, R., Balasubramanian, K., Wang, X. and Andrews, L. (2002) Infrared vibronic absorption spectrum and spin - orbit calculations of the upper spin-orbit component of the AU3 ground state. Journal of Chemical Physics, 117, 1614-1620. 

Recently Shokoohi et al. (14) obtained high resolution LIF spectra from the photolysis of ICN at 266 nm. Using these spectra, they were able to show that the population of the and F2 spin components associated with each rotational level varied with both rotational and vibrational quantum number. For CN radicals with v" = 0 and N" < 43 the population of F- level < F level, for N" = 43 the population of F- level F level, and for N" > 43 the population of F- level > F2 level. In the v" = 1 level more of the CN radicals are produced in the upper N" levels than in the lower levels and for these upper levels the population of F-l level > F2 level. In the v" = 2 level, no radicals are observed below N" = 17, and the population of Fj level > F level. These results can be qualitatively understood in the following manner. The iodine atom can be produced in the /2 and the spin-orbit states. Spin-orbit interaction between... 

A preferential population of one spin-orbit state has been found for OH in the photodissociation of HONO, where the higher state is more populated than predicted by statistics (Vasudev, Zare, and Dixon 1984 Shan, Vorsa, Wategaonkar, and Vasudev 1989). In NO(2n) generated via photolysis of CH3ONO (Lahmani, Lardeux, and Solgadi 1986 Briihlmann, Dubs, and Huber 1987), (CHa NNO (Dubs, Briihlmann, and Huber 1986 Lavi and Rosenwaks 1988), or (CHa CONO (Schwartz-Lavi, Bar, and Rosenwaks 1986) the lower state is slightly more populated than the upper state. The reason for this preference is not yet clear. 

Fig. 2. The variation of product cross sections with translational energy in the laboratory frame (upper scale) and the center-of-mass frame (lower scale) for the reaction of Kr" ( P) (in a statistical distribution of spin-orbit states) with SiH4. The solid line shows the total cross section. The dashed line shows the collision cross section given by the maximum of either the ion-induced dipole (LGS) or the hard sphere cross section. Reprinted with permission from Fisher and Armentrout (1990b). Copyright 1990, American Institute of Physics.

Suppose that the dissociation products are a polyatomic linear molecule and an atom (e.g., BrC C- + Br), and that the available energy is well above the vibrational energies of the BrC=C- fragment. Then the vibrational density of states must be included in the PED. If the upper Br atom spin-orbit state is ignored, the PED for a... 

Spin-orbit state selection by optical pumping is exemplified in Fig. 1 by the barium atom. The distribution in the spin-orbit levels of the metastable 6s5d term can be altered by irradiation on 5 of the lines of the 5d6p po <- 6s5d multiplet near 600 nm. If a cw laser is tuned to one of these atomic lines, then absorption and stimulated emission will occur at a rate proportional to the laser power. The upper level can also decay spontaneously to other lower spin-orbit levels, hence transferring jx)pulation permanently out of the initially pumped state. 

The 1 -h 2 photon study, via the valence B TIo state, extended the previous work. Long Franck-Condon progressions, arising from the valence character of the intermediate state, are evident in the ZEKE spectra of both spin-orbit components. In the lower spin-orbit component, the vibrational progression extends to at least = 62, and in the upper state as high as = 34. The spectrum in the range 75 000 to 80 000 cm of the lower spin-orbit state, which was recorded via v = 15, is shown in Figure 6. 

The thermochemistry and results summarized in Table 2.3 are based upon the assumption that only ground electronic state halogen atoms are involved as reactants and products. The energy difference between the upper ( A/2) and lower ( 3/2) spin orbit states are 1.2, 2.5, 10.5, and 21.7 kcal mole for the halogen series. For room temperature equilibrium conditions, only F( Pi/2) can affect the reactant side of the equation. According to theoretical considerations, 2 1,2 should react more slowly than the Pzi2 state. Simple correlation diagrams, show that the X( Fi/2) state correlates with the X ( Fi/2) product state in X -I- HX reactions. The possibility that /( Fi/2) is a product from the Br, Cl, and F + HI reactions has been excluded by direct tests for /( Fi/2 — 7 3/2) emission. In contrast,... 

Spin-orbit interactions mix states with the same J but different L 8 by second (or higher) order perturbations, such perturbations become important when the separation between the levels is small. The spin-orbit coupling constants ( 4/) increase more rapidly through the rare earth series with increasing number of /-electrons than do the F s. This results in the breakdown of L 8 coupling even more near the middle of the rare earth series, because of the greater population of the upper... 

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