Integrated band intensity versus temperature for the ν1, ν2, ν5, and ν6 bands of cyanoacetylene

The integrated intensity, AB, of the ν1, ν2, ν5, and ν6 bands of cyanoacetylene were determined experimentally at different temperatures between 225 and 325 K. We have deduced that these values are in perfect agreement with the expression AB = SvZv[1 − exp(-hcvnkT)](TT0)β, where Sv is the vibrational band strength, Zv is the vibrational partition function, vn is the band center, and β is a dimensionless constant, the value of which ranges from 14 up to 45. Within 190 K ≤ T ≤ 350 K, two values of AB were compared, the first given by the empirical model with β to be determined from experimental measurements, and the second given by the theoretical model with zero-rated β fixed to zero.