Abstract

It has been suggested that the line width of ions in molecular clouds is narrower than that of the co-existing neutral particles, which has been interpreted as an indication of the decoupling of neutral turbulence from magnetic fields within a partially ionized environment. We calculate the principal component analysis (PCA) correlation coefficients of CCH versus HCO and HCN versus HCO. We find aside from HCN, CCH could also be strongly spatial correlated with HCO in high-mass star-forming regions. CCH and HCO line emissions are strongly spatial correlated with each other in 48 per cent sources with a PCA correlation coefficient over 0.7. So, we investigate the ambipolar diffusion (AD) effect using CCH and HCO lines as a neutral/ion pair in a sample of 129 high-mass star-forming clumps. We conduct a careful analysis of line widths of the CCH-HCO pair pixel-by-pixel in 12 sources, which show a strong correlation in CCH-HCO emission and no obvious outflows or multiple velocity components. The mean velocity dispersion of CCH is about the same as HCO in 12 sources. In low-density regions of most sources, CCH shows a broader velocity dispersion than HCO. However, the AD effect is not significant from a statistical point of view. © 2024 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society.