ABSOLUTE INFRARED INTENSITIES IN HCN AND DCN

Author Institution: Metcalf Research Laboratory, Brown UniversityThe absolute intensities of all three fundamentals of HCN and DCN in the infrared spectrum were measured, using the pressure-broadening technique of Wilson and Wells. The measurements were made at a broadening pressure of 4 atmospheres of nitrogen in a double beam spectrophotometer. The intensities obtained are given in Table 1. [FIGURE] Using the potential function, $2V \times 10^{-5} = 5.62 r_{C-H^{2}}+18.85 r_{C-N^2} 0.44 r_{C-N}r_{C-N}$, which is obtained from the frequencies of Table 1, the bond moments and derivatives listed in Table 2 are obtained. [FIGURE] Smyth's value of the dipole moment of HCN, 2.93 D, was used to calculate the bond moments. The intensity of two of the three peaks in the anomalous band, $\nu_{1}$, of HCN varies as $P_{HCN}{^{2}}$ and are probably due either to dimer or collision complexes. If as much as 75 percent of the observed intensity is due to this source, as seems reasonable, a value of $\partial \mu/\partial_{r_{CN}}$ which agrees exactly with that of DCN is obtained