Raman spectra of some indo‐, thia‐ and selena‐carbocyanine dyes

Raman spectra of some indo‐, thia‐ and selena‐carbocyanine dyes have been measured. The bands are assigned to the modes associated with the methine chain, end chromophore and methyl/ethyl group based on a comparison of the positions of the bands for a series of dyes with similar structures and those for 1,2,3,3–tetramethylindoleniumiodide and 2–methyl–3–ethylbenzothiazolium iodide, compounds related to the end chromophore of indo‐ and thia‐carbocyanine dyes, respectively.