Abstract
Absorption spectra of m-nitronitrosobenzene monomer in crystalline state as well as in solution have been measured quantitatively in the visible and the ultraviolet regions. In its π-band of the ultraviolet region, the general rule about the π-band of the benzene ring was found to hold also for the present case. In regard to the nitroso band of the visible region, the absorption by linearly polarized light with the electric vector vibrating perpendicular to the C–N–O bond was hyperchromic to the absorption by the light with those vibrating parallel to it. This result suggests that the green colour of m-nitronitrosobenzene is due to the electronic transition polarized perpendicularly to the C–N–O bond.