FTIR Spectroscopy of Solid Parahydrogen in the NIR/VIS Region

We report the results of FTIR measurements of solid parahydrogen at 12.5 K in the spectral region 9 000 – 16 500 cm −1 using an internal multireflection cell with 14 cm optical path length. We find several new ro–vibrational transitions such as the single transition W 2 (0) at 10241.07 cm −1 and double transitions among which we consider the most interesting ones to be Q 2 (0) + Q 1 (0), due to its unexplained induction mechanism, and Q 2 (0) + S 1 (0) due to its fine structure, revealing non–resonant hopping of rotational excitations. Furthermore we find absorption features at 8650–8670 cm −1 and at 8980–9000 cm −1 which we interpret as the triple transitions Q 1 (0) + Q 1 (0) + S 0 (0) and S 1 (0) + Q 1 (0) + S 0 (0), which acquire intensity from nearby double transitions. At 12 788 cm −1 we find the triple transition S 1 (0) + Q 1 (0) + Q 1 (0).