Knowledge Bank

The $\lambda$4050A group of C3 bands appearing in the emission spectra of comets and in the absorption spectra of cool stars have recently been observed in several laboratory sources including oxy-hydrocarbon flames. As part of a programme of intensity measurements on band systems of astrophysical interest, the emission spectra of the luminous region of fuel-rich oxy-acetylene flames have been examined over the wavelength region $\lambda\lambda$3800 - 4300A. The $\lambda$4050A group and an associated underlying violet continuum with maxima at $\lambda$4000A and $\lambda$4300A were observed in addition to bands of C2, CH, and CN. Relative intensity measurements on these spectra produced under different flame conditions are reported and discussed.