Rotational and vibrational temperatures measured in a chemiluminescent flame from FTIR Bi 2 emission spectra

Abstract

Rotational and vibrational temperatures of the Bi 2 dimer have been measured in a chemiluminescent flame. Emission spectra of the Bi 2 a 3Σ u +(a 11 u)→X 1Σ g +(X0 g +) transition in the near-infrared region were recorded with a FTIR spectrometer. High-resolution spectra of the 0-3, 0-8, 0-9, 2-3, 4-1, 6-0, 6-1, and 7-1 bands served for the determination of the rotational temperature. It was observed that both rotational and vibrational levels are described well by Boltzmann distributions. The average rotational temperature (T rot =324±12 K) was found to be consistent with the vibrational temperature (T vib =316±15 K) . The study has shown that such a very heavy molecule as Bi 2 can serve for temperature measurements by optical emission as reported so far only for light molecules.