We have recorded the Raman spectra of H2 and D2 clusters in cryogenic free jets from a 50 micron nozzle and a wide range of source conditions.
The weak Raman spectra of the (oD2)N clusters have been recorded near the Q(0) line at 2993.5 cm-1 and S1(0) line at 3166.3 cm-1 of the oD2 monomer. Small clusters from dimer to pentamer can be identified, in a similar way to para-H2 clusters [1]. New transitions for (oD2)2 have been measured, and compared with recent ab-initio calculations [2]. Larger clusters are also obtained by changing the source conditions.
Mixtures with controlled ratios of ortho-H2 to para-H2 have been expanded. The Raman spectra of the pure pH2, oH2, and the mixed oH2-pH2 dimers have been recorded in the regions of the vibrational Q(0) and Q(1) lines of the monomer [3].
We have also recorded the region of the S1(0) line of pH2 at 4498.4 cm-1. New transitions corresponding to the (pH2)2 dimer and (pH2)3 trimer have been observed.
[1] G. Tejeda, J. M. Fernandez, S. Montero, D. Blume and J. P. Toennies, "Raman spectroscopy of small para-H2 clusters formed in cryogenic free jets", Phys. Rev. Lett. 92, 223401 (2004).
[2] R. J. Hinde, "A six-dimensional H2-H2 potential energy surface for bound state spectroscopy", J. Chem. Phys. 128, 154308 (2008).
[3] S. Montero, J.H. Morilla, G. Tejeda and J.M. Fernandez, "Experiments on small (H2)N clusters", Eur. Phys. J. D 52, 31-34 (2009).
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