LOW‐TEMPERATURE PHOTOACOUSTIC SPECTROSCOPY OF PORPHYROPSIN IN THE INTACT RETINA OF THE CREEK CHUB, Semotilus atromaculatus

Abstract

Abstract— The photoacoustic spectra of porphyropsin in the creek chub (Semotilus atromaculatus) have been successfully measured on single retinae of small size (< 0.5 cm in diameter) at low temperatures. The relative intensities of the spectra, corresponding to the thermal release, are strong enough to be comparable to those for the big cattle retina. The photoacoustic spectrum of porphyropsin at – 167°C exhibits a principal maximum at 540 nm with a small shoulder near 580 nm. A sequence of porphyropsin bleaching resulted from thermal reaction has been clearly observed above ‐90°C.