Emission spectroscopy of IR laser-induced processes in ultra-dense deuterium D(0): Rotational transitions in D(0) with spin values s = 2, 3 and 4

The emission spectrum induced in ultra-dense deuterium D(0) by a 1064 nm pulsed YAG laser with 0.4 J pulses is strongly dependent on the amount of D(0) formed. With D2 pressure below 10−2 mbar at the D(0) generator and no D(0) layer on the metal surface, line spectra can be observed with numerous lines due to metal and gas atoms. When a D(0) layer exists on the generator surface, these lines disappear. A different pattern of emission lines and bands is then found. Several peaks are observed which agree well with the rotational transitions of rotating D-D pairs in D(0) from theory. The peak widths are approximately 20 cm−1. A prominent peak at 760 nm corresponds to spin state s = 3 in D(0) from a rotational transition J = 1 → 0. This gives an experimental D-D distance in this state of 5.052 ± 0.003 pm that is only 0.25% larger than predicted by theory and calculations. The existence of these rotational lines strongly supports the cluster model of D(0) described previously. At a few hundred mbar pressure, a red-emitting apparently self-focused beam is formed by the laser beam. The expected Balmer lines are weak or absent.