Isotope Shift in Neutral Carbon

There is a possibility that the discrepancy between the experimental values of spectral isotope shift in light elements and the values calculated by including nuclear motion may be reduced by using improved one-electron wave functions. In order to investigate this possibility and at the same time to make a comparison with recently obtained experimental data, the shift of the transition $2p^2{}_{}{}^1{}_{}{}^{}S-2p3s{}_{}{}^1{}_{}{}^{}P(\lambda =2478.5\mathrm{}\mathrm{A})$ of neutral carbon has been calculated using Hartree one-electron functions without exchange. The functions for the $2p3s$ configuration were calculated by the author for this purpose. The agreement with the experimental value is comparable to that obtained for other elements with this type of function. A comparison of the term shifts is made for both the ${}_{}{}^3{}_{}{}^{}P$ and ${}_{}{}^1{}_{}{}^{}S$ terms of the $2p^2$ configuration using Hartree functions with and without exchange and analytic functions of the Morse, Young, and Haurwitz type. The use of functions with exchange produced a significant change in the calculated term shifts which indicates that it may be possible to improve the agreement between calculated and observed transition shifts.