  The brightest observed emission line in many star-forming galaxies is the
[CII] 158 micron line, making it detectable up to z~7. In order to better
understand and quantify the [CII] emission as a tracer of star-formation, the
theoretical ratio between the [NII] 205 micron emission and the [CII] 158
micron emission has been employed to empirically determine the fraction of
[CII] emission that originates from the ionized and neutral phases of the ISM.
Sub-kiloparsec measurements of the [CII] 158 micron and [NII] 205 micron line
in nearby galaxies have recently become available as part of the Key Insights
in Nearby Galaxies: a Far Infrared Survey with Herschel (KINGFISH) and Beyond
the Peak (BtP) programs. With the information from these two far-infrared lines
along with the multi-wavelength suite of KINGFISH data, a calibration of the
[CII] emission line as a star formation rate indicator and a better
understanding of the [CII] deficit are pursued. [CII] emission is also compared
to PAH emission in these regions to compare photoelectric heating from PAH
molecules to cooling by [CII] in the neutral and ionized phases of the ISM. We
find that the [CII] emission originating in the neutral phase of the ISM does
not exhibit a deficit with respect to the infrared luminosity and is therefore
preferred over the [CII] emission originating in the ionized phase of the ISM
as a star formation rate indicator for the normal star-forming galaxies
included in this sample.
