Spectroscopic studies of the cresols

Summary

Part A:—The emission spectrum of meta-cresol, obtained by means of a controlled transformer discharge through the flowing vapour, is recorded on the Hilger medium quartz (E₂) spectrograph. The emission spectrum consists of fifteen bands in the region 2750–2920 Å superposed over a continuum beginning at about 2770 Å and extending to beyond 3100 Å. The discrete emission spectrum is the counterpart of the near ultra-violet absorption spectrum of meta-cresol vapour (Part B). The electronic transition involved in the discrete band system is interpreted as¹A′ –¹A′. A vibrational analysis of the band system is proposed in terms of the ground state vibrational frequencies 200, 401, 735 and 1003 cm.⁻¹ and the excited state frequencies 116, 188 and 251 cm.⁻¹

Part B:—The absorption spectrum of meta-cresol vapour, using absorption paths ranging from 100–250 cm. and temperatures from 0–30°C., is recorded on the Hilger large quartz (E₁) spectrograph. About fifty-five bands are obtained in the region 2580–2810 Å. A vibrational scheme for the band system is proposed in terms of the excited state vibrational frequencies 116, 188, 251, 469, 696, 964 and 1031 cm.⁻¹ and the ground state frequencies 200, 248 and 401 cm.⁻¹