Top: analytical representation of the third peak of σ_cont(λ,T) with a Gaussian function, σ₃(λ,T), centred at 68 000 cm^-1 for temperatures between 150 and 800 K. Middle: variation of the amplitude A₃ of the third Gaussian function as a function of the temperature. The variation can be fitted by a linear function. Bottom: variation of the standard deviation s₃(T) /T of the third Gaussian function as a function of the temperature. The variation can be fitted by a decreasing exponential function.