  We present an experimental comparison of photoacoustic responsivities of
common highly absorbing carbon-based materials. The comparison was carried out
with parameters relevant for photoacoustic power detectors and
Fourier-transform infrared (FTIR) spectroscopy: we covered a broad wavelength
range from the visible red to far infrared (633 nm to 25 um) and the regime of
low acoustic frequencies (< 1 kHz). The investigated materials include a candle
soot-based coating, a black paint coating and two different carbon nanotube
coatings. Of these, the low-cost soot absorber produced clearly the highest
photoacoustic response over the entire measurement range.
