Qualitative interpretation=A05-m5ai






[Legenda]
[Contents of the thesis]
[Comments]






[Legenda]
[Contents of the thesis]
[Comments]

Qualitative interpretation=A05-m5aii

In the measured differential cross section of the chemi-ioniation reaction M + X₂ M⁺ + X^- a small maximum is observed in the small-angle region, seen in all cross-section curves,

that cannot be explained by a classical model stating the general shape of the deflection curve as sketched in figure A05-m5aii-F2

and the equation for the differential cross section

$\displaystyle I(\theta)=\frac{1}{\sin \, \theta}\sum_{i=1,2,\ldots}\ P_{b_{i}}(1-P_{b_{i}})b_{i}\bigg\vert\frac{\dr b_{i}}{\dr {{\mit\Theta}. }}\bigg\vert.$ (E1)

Quantum mechanically this phenomenon can be explained by constructive interference of some contributions, for instance the contributions of the two net repulsive branches of the b- $\tau$ curve. Because of the nearly equal slopes and about equal collision parameters of these branches at small scattering angles, the wavelength of the interference is rather long; a rough estimate has shown that the wavelength has a value of a few degrees at the energies used, which is of the same order of magnitude as the widths of the measured maxima.
.

Although we have only considered a two-contribution interference instead of four contributions, this interference can explain the observed bump in the differential cross section at small angle.