Experiments on small (H2)N clusters
Laboratory of Molecular Fluid Dynamics, Instituto de Estructura de la Materia, CSIC, Serrano 121, 28006 Madrid, Spain
Corresponding author: a email@example.com
Published online: 6 February 2009
The nucleation process of small hydrogen clusters has been studied in detail with space, time, and number size resolution on the basis of supersonic expansions of the gas through a cryogenic nozzle operating in the thermal range 24 < T <110 K. The diagnostic of the jet medium is based on high sensitivity (few photons/sec) Raman spectroscopy with very high spatial resolution (m), enabling for quantitative measurements with time resolution in the domain of nanoseconds. Temperatures down to 0.1 K have been attained in the jet at a collisional rate low enough to avoid sudden freezing of the gas. Clusters between two and eight molecular units are observed size-resolved. Features of the ortho-ortho and ortho-para hydrogen dimers, and the role of three-body collisions for nascent dimers and trimers are reported.
PACS: 36.40.-c – Atomic and molecular clusters / 33.20.Fb – Raman and Rayleigh spectra / 05.30.Jp – Boson systems
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2009