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Impulsively generated sausage wave trains in coronal structures are importantfor interpreting a substantial number of observations of quasi-periodic signalswith quasi-periods of order seconds. We have previously shown that the Morletspectra of these wave trains in coronal tubes depend crucially on thedispersive properties of trapped sausage waves, the existence of cutoff axialwavenumbers and the monotonicity of the dependence of the axial group speed onthe axial wavenumber in particular. This study examines the difference a slabgeometry may introduce, for which purpose we conduct a comprehensive eigenmodeanalysis, both analytically and numerically, on trapped sausage modes incoronal slabs with a considerable number of density profiles. For the profiledescriptions examined, coronal slabs can trap sausage waves with longer axialwavelengths, and the group speed approaches the internal Alfv\'en speed morerapidly at large wavenumbers in the cylindrical case. However, common to bothgeometries, cutoff wavenumbers exist only when the density profile fallssufficiently rapidly at distances far from coronal structures. Likewise, themonotonicity of the group speed curves depends critically on the profilesteepness right at the structure axis. Furthermore, the Morlet spectra of thewave trains are shaped by the group speed curves for coronal slabs and tubesalike. Consequently, we conclude that these spectra have the potential fortelling the sub-resolution density structuring inside coronal structures,although their detection requires an instrumental cadence of better than $\sim1$ second.

Impulsively generated wave trains in coronal structures: II. Effects of transverse structuring on sausage waves in pressureless slabs