2Z* state

CASSCF calculations for the lowest 2Z+ and 2n state of CCCN in this geometry. 

Assuming that these lactonium salts exist in the EZ form 21, the two transition states yielding 21 and 21 can be illustrated by 2j> and ]] respectively. In 2Z> the bond to be broken is antiperiplanar to the non polar ( -Cj bond whereas in 21> the bond to be broken is antiperiplanar to the C- -0- polar bond. In other words, in 26 the electron pair orbital of the C5 - O5 

Fig. 2-10.—The interaction of Bpin angular momentum and orbital angular momentum to form the total angular momentum for the states 2Z>j and 2D .

It appears that process (54) alone cannot explain the fact 4>n, = 1.4 at 1470 A., since the process (54) followed by process (59) gives 4>n2 1. Of course, the N atom may be formed in the (2Z)) state, in which case it may react with N20 to produce N2 + NO. Such a mechanism is, however, still incapable of explaining the high N quantum yield. The process (53) followed by (57) and (58) would explain 4>n, = 1.4. 

In the homonuclear AX case, e.g. a proton-proton two-spin system, the 180" pulse affects both nuclei. The doublet vectors are reflected at the x z plane. Inverting the precession states of all other coupling nuclei, the 180" pulse also inverts rotation of both AX components (Fig. 2.38(c)). At time 2z, the vectors will be aligned antiparallel along + x (Fig. 2.38(c)) the resultant is zero and no signal will be detected. 

AlO is another product from photolysis of HAIOH which is not observed in the Infrared studies (1 ) since the AlO 917 cm l band (13) is obscured by the presence of other product bands. In multiple-collision studies, Gole and Oblath observe emission from the B(2z" ) state of AlO postulating that the state is col-llsionally activated by HAIOH since single-collision studies display no AlO emission. 

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