State-specific angular distributions

Lasers can also be used to determine the state-resolved angular distributions when a specific AB(v, /) state is measured by novel techniques, such as Doppler profile or ion imaging. 

The dependence of <6> on product vibrational state (Table 2) is rather weak, with only a gradual increase in <0> with increasing vibrational energy and no consistent mode specificity apparent. The vibrationally state resolved angular distributions corresponding to the states listed in Table 2 have not been plotted ti re, but they tend to have the same general appearance as indicated in Fig. 3. 

Keil and co-workers (Dhamiasena et al [16]) have combined the crossed-beam teclmique with a state-selective detection teclmique to measure the angular distribution of HF products, in specific vibration-rotation states, from the F + Fl2 reaction. Individual states are detected by vibrational excitation with an infrared laser and detection of the deposited energy with a bolometer [30]. 

A simple measurement of the total photoionization cross section (isotropic sample, cross section measured at a specified photon energy, integrated over all photoejection angles, without specification of the internal state of the photoion, without determination of ms of the ejected electron) contains no information about the distribution of Z, m -values of the ejected electron. However, measurable properties of the photoionization event can provide information about the mechanism of the photoionization process. The frequently measured quantities included f3, Aq, and A. The ft quantity describes the angular distribution of the photoelectrons and is defined analogously to the (3 for photodissociation (see Section 7.2.4), Ajp is the alignment ( Mm distribution) of the photoion. A (not to be confused with the spin-orbit constant) or alternatively P, is the spin-polarization of the ejected electron, which is relevant when the photoion has nonzero spin. 

Angular distributions for scattering into a specific final quantum state, NO(v=l,J=l 1/2,S2=1/2), are illustrated in figure 5 for scattering from Ag(lll) and Ag(llO). The full width at half maximum (in degrees) of the angular distributions, Xf, are reported for the surfaces studied in table 1. 

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