Comparing Infrared Star-Formation Rate Indicators with Optically-Derived
  Quantities
  We examine the UV reprocessing efficiencies of warm dust and polycyclic
aromatic hydrocarbons (PAHs) through an analysis of the mid- and far-infrared
surface luminosity densities of 85 nearby H$\alpha$-selected star-forming
galaxies detected by the volume-limited KPNO International Spectroscopic Survey
(KISS). Because H$\alpha$ selection is not biased toward continuum-bright
objects, the KISS sample spans a wide range in stellar masses
($10^8$-$10^{12}\rm{M}_\odot$), as well as H$\alpha$ luminosity
($10^{39}$-$10^{43}\rm{ergs/s}$), mid-infrared 8.0$\mu$m luminosity
($10^{41}$-$10^{44}\rm{ergs/s}$), and [Bw-R] color (-.1-2.2). We find that
mid-infrared polycyclic aromatic hydrocarbon (PAH) emission in the Spitzer IRAC
8.0$\mu$m band correlates with star formation, and that the efficiency with
which galaxies reprocess UV energy into PAH emission depends on metallicity. We
also find that the relationship between far-infrared luminosity in the Spitzer
MIPS 24$\mu$m band pass and H$\alpha$-measured star-formation rate varies from
galaxy to galaxy within our sample; we do not observe a metallicity dependence
in this relationship. We use optical colors and established mass-to-light
relationships to determine stellar masses for the KISS galaxies; we compare
these masses to those of nearby galaxies as a confirmation that the
volume-limited nature of KISS avoids strong biases. We also examine the
relationship between IRAC 3.6$\mu$m luminosity and galaxy stellar mass, and
find a color-dependent correlation between the two.
