Solvent Effect on the O2(bΣg+) → O2(a1Δg) Emission Spectrum

The effect of solvent on the O 2 (b 1 Σ g + ) − O 2 (a 1 Δ g ) fluorescence spectrum has been examined. The emission maximum in solution is red-shifted relative to the gas-phase value of 1908 nm, and the extent of the shift increases as the refractive index, n, of the solvent increases. This observation is consistent with previously published data on the O 2 (a 1 Δ g ) − O 2 (X 3 Σ g - ) transition. Although solvent-dependent changes in the wavelength of the infrared O 2 (b 1 Σ g + ) − O 2 (a 1 Δ g ) emission peak are more pronounced than on the near-infrared O 2 (a 1 Δ g ) − O 2 (X 3 Σ g - ) peak, the effect of solvent on the respective transition energies is roughly equivalent. Plots of the O 2 (b 1 Σ g + ) − O 2 (a 1 Δ g ) emission maximum against n, or functions of n, indicate that a number of variables likely contribute to the oxygen−solvent interaction.