Conclusion We have demonstrated a photoacoustic apparatus and technique capable of detecting a minimum absorptivity on the order of 4 X IO-'O/cm. To demonstrate this sensitivity, we recorded the 4-0 and 5-0 0-H overtone spectra of phenol in the gas phase using the vapor present over the solid at room temperature. Several modifications to the standard methods of overtone photoacoustic spectroscopy were made to achieve this ...
