Nondipole and interchannel-coupling effects in the photodetachment of ${\text{Cl}}^{-}$

Nondipole photodetachment parameters for the $3p$ subshell of ${\text{Cl}}^{-}$ are calculated using relativistic random-phase approximation (RRPA). Interchannel-coupling effects on nondipole photodetachment parameters for the $3p$ subshell are studied with different degrees of truncation of the RRPA. It is inferred from the present investigations that the shape resonance in the photodetachment cross-section profile and the positions of the Cooper minima are sensitive to interchannel coupling. An analysis of the angular distribution of the photoelectrons reveals how the Cooper minima in the dipole and the quadrupole channels introduce a complex energy dependence, with peaks and zeroes, of the nondipole asymmetry parameter $\zeta$.

Figure 1

Quadrupole $\left(E2\right)$ cross section of the $3p$ shell of ${\text{Cl}}^{-}$ for two levels of truncation of RRPA: channels from $3p+3s$, eight channels (solid line) and from $3p$, six channels (dotted line). Vertical lines indicate thresholds.

Figure 2

Absolute values of the quadrupole $\left(E2\right)$ matrix elements for the channels from $3p_{1/2}$ subshell (upper panel) and from the $3p_{3/2}$ subshell (lower panel). The respective solid line and dotted line represent matrix elements of eight-channel and six-channel calculations. The matrix elements of the channels $3p_{3/2}\to p_{3/2}$ and $3p_{3/2}\to p_{1/2}$ are almost identical so that the transition is designated only as $3p_{3/2}\to p$. Vertical lines indicate thresholds.

Figure 3

Nondipole angular distribution asymmetry parameter ${\zeta }_{3p_{1/2}}$. Vertical lines indicate thresholds.

Figure 4

Dipole cross section of the $3p$ subshell in the Cooper minimum region [11].

Figure 5

Comparison of cross section of $3p$ shell for various degrees of truncations at higher energy. Solid line represents the result of the 14-channel calculation, dashed line represents that of eight-channel calculation, and dotted line that of six-channel calculation. Vertical lines indicate thresholds.

Figure 6

Absolute values of the matrix elements which contribute to quadrupole $\left(E2\right)$ cross section for $3p_{1/2}$. Vertical lines indicate thresholds.

Figure 7

Terms in expression for ${\zeta }_{3p_{1/2}}$, Eq. (7), with appropriate sign so that sum of these terms yields ${\zeta }_{3p_{1/2}}$.

Figure 8

$\text{cos}\Delta$, the cosine of the phase-shift difference between $E1$ and $E2$ channels, as a function of photon energy. Solid line corresponds to $\delta E1\left(p_{1/2}\to d_{3/2}\right)-\delta E2\left(p_{1/2}\to f_{5/2}\right)$, dashed line corresponds to $\delta E1\left(p_{1/2}\to s_{1/2}\right)-\delta E2\left(p_{1/2}\to f_{5/2}\right)$, dotted line corresponds to $\delta E1\left(p_{1/2}\to d_{3/2}\right)-\delta E2\left(p_{1/2}\to p_{3/2}\right)$, and dash-dotted line corresponds to $\delta E1\left(p_{1/2}\to s_{1/2}\right)-\delta E2\left(p_{1/2}\to p_{3/2}\right)$.