Photolysis of indan-1, 2, 3-trion (1a), benzo [b] furan-2, 3-dione (1b), and N-methylisatin (1c) in argon matrix either with or without oxygen at 10 K was investigated by IR spectroscopy in combination with DFT calculations. The results indicate that while 1a and 1b gave the products mixture as a result of α-cleavage, followed by decarbonylation, 1c was rather photostable under similar conditions. However, when the irradiation was carried out in ...