The photophysical behavior of a new type triplet sensitizers-N-methyl-2-aryloylmethyiene-β-naphthiazoline has been studied in this work. The absorption spectra

quantum yield of fluorescence and phosphorescence of these compounds have been measured. It was found that the sensitizers studied have higher molar absorption coefficient (104) than that of the usual sensitizers. In addition

they have high inter-system corssing efficiency. In the presence of different sensitizers

we measured the rate of photoisomerization of t-stilbene to cis-stilbene as a method for evaluating the efficiency of these compounds. Results indicated that the new type of sensitizers is an efficient one.