We consider six isomeric groups (CH_3_N, CH_5_N, C_2_H_5_N, C_2_H_7_N, C_3_H_7_N, and C_3_H_9_N) to review the presence of amines and aldimines within the interstellar medium (ISM). Each of these groups contains at least one aldimine or amine. Methanimine (CH_2_NH) from CH_3_N and methylamine (CH_3_NH_2_) from CH_5_N isomeric group were detected a few decades ago. Recently, the presence of ethanimine (CH_3_CHNH) from C_2_H_5_N isomeric group has been discovered in the ISM. This prompted us to investigate the possibility of detecting any aldimine or amine from the very next three isomeric groups in this sequence: C_2_H_7_N, C_3_H_7_N, and C_3_H_9_N. We employ high-level quantum chemical calculations to estimate accurate energies of all the species. According to enthalpies of formation, optimized energies, and expected intensity ratio, we found that ethylamine (precursor of glycine) from C_2_H_7_N isomeric group, (1Z)-1-propanimine from C_3_H_7_N isomeric group, and trimethylamine from C_3_H_9_N isomeric group are the most viable candidates for the future astronomical detection. Based on our quantum chemical calculations and from other approximations (from prevailing similar types of reactions), a complete set of reaction pathways to the synthesis of ethylamine and (1Z)-1-propanimine is prepared. Moreover, a large gas-grain chemical model is employed to study the presence of these species in the ISM. Our modeling results suggest that ethylamine and (1Z)-1-propanimine could efficiently be formed in hot-core regions and could be observed with present astronomical facilities. Radiative transfer modeling is also implemented to additionally aid their discovery in interstellar space.
The electron-impact widths for 30 Zr III lines were calculated using the modified semi-empirical (MSE) method. For two Zr II and four Zr III astrophysically important UV lines, only electron-impact widths are given, since for their calculation the experimental oscillator strengths were used and consequently the accuracy of the parameters is lower than in the case of other lines. The influence of the electron-impact mechanism on line shapes and equivalent widths in hot star atmospheres was also considered. The impact of the electron-impact broadening effect on abundance determination, particularly its effect on "zirconium conflict" is discussed as well.
We seek to present accurate and extensive transition data for the ZrIII ion. These data are useful in many astrophysical applications. We used the multiconfiguration Dirac-Hartree-Fock and relativistic configuration interaction (RCI) methods, which are implemented in the general-purpose relativistic atomic structure package GRASP2018. The transverse-photon (Breit) interaction, vacuum polarization, and self-energy corrections are included in the RCI computations. Energy spectra were calculated for the 88 lowest states in the ZrIII ion. The root-mean-square deviation obtained in this study for computed energy spectra from the experimental data is 450cm^-1^. Electric dipole (E1), magnetic dipole (M1), and electric quadrupole (E2) transition data, line strengths, weighted oscillator strengths, and transition rates are computed between the above states together with the corresponding lifetimes. The computed transition rates are smaller than the experimental rates and the disagreement for weaker transitions is much larger than the experimental error bars. The computed lifetimes agree with available experimental values within the experimental uncertainties.
