Electron-impact broadening of radio recombination lines of atomic hydrogen for different \u394n

In 1967 Griem gave a general formula for the electron-impact broadening of radio recombination lines, and an approximate expression for the width of the \u394n = 1 lines. Here his general formula is calculated numerically for higher values of \u394n, and an approximate expression is fitted to the results for \u394n up to 70. It is shown that, for the lines with different n and \u394n near a given frequency \u3bd, the calculated widths increase monotonically up to n > 300. This result does not agree with the maximum found near n 48 200 by Bell et al (2000 Publ. Astron. Soc. Pac. 112 1236) for the astronomical sources W51 and Orion A at 6 GHz. Thus this mystery is not resolved by the present calculations.NRC publication: Ye