Collision strengths and rate coefficients of electron-impact excitation and photo-excitations of Ca IV*

We will report various features of collision strengths ($\Omega$) for

electron-impact excitation and corresponding Maxwellian averaged

effective collision strengths of Ca IV obtained for 1431 excitations among

54 fine structure levels belonging to $1s^22s^22p^63s^23p^5$,

$1s^22s^22p^63s3p^6$, $1s^22s^22p^63s^23p^43d$, $1s^22s^22p^63s^23p^44s$,

and $1s2^2s^2p^6 3s^33p^44p$ configurations. The first excitation of

wavelength 3.2 $\mu$m, forbidden $^2P_{3/2} - ^2P_{1/2}$ transition of

the ground configuration $3s^23p^5$, show prominent resonances in the

low and intermedicate energy range indicating high probability of detection

of Ca IV in the infrared region by the James Webb Space Telescope. We also

notice significant difference in strength between excitations from

$^2P_{3/2}$ and $^2P_{3/2}$ to  $^2S_{1/2}$. The high lying dipole allowed

transitions show rising trend in $\Omega$. Calculations

were carried out using relativistic Breit-Pauli R-Matrix (BPRM) method.

We will also present an extensive set of photoexcitation parameters of

Ca IV of types E1, M1, E2, M2 among 387 levels obtained in Breit-Pauli

approximation using the code SUPERSTRUCTURE.