  The sample of IRAS galaxies with spectral energy distributions that peak near
60 microns are called Sixty Micron Peakers (SMPs or 60PKs). Their generally
peculiar and amorphous morphologies, hot dust and lack of a cirrus component
have been interpreted as being indicative of a recent interaction/merger event.
Mid-infrared spectra of eight SMPs, obtained with ISOPHOT-S in the ~2-11 micron
band are presented. Four of the observed sources are H II region-like (H2)
galaxies, three are Seyfert 2 and one is unclassified. Emission attributed to
Polycyclic Aromatic Hydrocarbons (PAHs) at 6.2, 7.7 and 8.6 micron is
ubiquitous in the spectra. The PHOT-S spectrum of the H2 galaxy IRAS 23446+1519
exhibits a bright 11.04 micron line and an 8.6 micron feature of comparable
size to its 7.7 micron feature. [S IV] emission at 10.5 micron was detected in
three of four H2 galaxies and in one Seyfert 2 galaxy. The ratio of the 7.7
\textmu m PAH feature to the continuum at 7.7 micron (PAH L/C) divides the
eight SMPs at a ratio greater than 0.8 for H2 and less than 0.8 for Seyfert
galaxies. An anti-correlation between PAH L/C and the ratio of the continuum
flux at 5.9 micron to the flux at 60 micron is found, similar to that found in
ultraluminous infrared galaxies. Silicate absorption at approximately 9.7
micron was observed in the Seyfert 2 galaxy, IRAS 04385-0828 and in IRAS
03344-2103. The previously unclassified SMP galaxy IRAS 03344-2103 is probably
a Seyfert 2.
