High-resolution infrared spectrum of thev₃andv₆bands of HCF₃and of their hot bands

The infrared spectrum of fluoroform has been recorded between 480 and 730 cm-1 at a resolution of 0·03 cm-1. The v 6 perpendicular band at 507·8228 (6) cm-1, heavily perturbed by an l(2,2) type rotational resonance, has been analysed in the P and R as well as in the Q branches. The v 3 parallel band at 700·1009 (6) cm-1 has also yielded molecular constants including C″ - C′. Each of these bands is accompanied by hot bands among which v 3 + v 6 - v 6 and 2v 6 - v 6 deserved special attention since both the upper and lower states of these transitions are perturbed.