Polycyclic aromatic hydrocarbon size tracers

Abstract We examine the dependence of polycyclic aromatic hydrocarbon (PAH) band intensity ratios as a function average number carbon atoms and assess their effectiveness tracers for PAH size, utilising data, models, tools provided by NASA Ames Infrared Spectroscopic Database. To achieve this, we used spectra from mixtures PAHs different ionisation fractions, following size distribution. Our work, congruent with earlier findings, shows that include 3.3 μm provide best small-to-intermediate sized PAHs. In addition, find sum 15-20 features (I$_{\Sigma _{15-20}}$) 6.2 or 7.7 bands also serve good in case PAHs, objects under similar distribution presented models. For distributions, application scaling factor to I6.2/I$_{\Sigma _{15-20}}$ ratio can estimates population within sources. Employment I7.7/I$_{\Sigma be particular interest JWST observations limited only ∼5-28 MIRI(-MRS) coverage.