Infrared spectroscopy of hydrogen-doped liquid helium

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Trottier, Alexandre
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University of Guelph

Samples of liquid helium and hydrogen-doped liquid helium were irradiated using a 3 MeV proton beam. The mid-infrared spectra of the samples were recorded between 0.3 and 1.8 μm. In the hydrogen-doped liquid helium spectra we observe several rotational lines from different vibrational bands of the e\sp3Σ\sbspu+⟶a\sp3Σ\sbspg+ hydrogen electronic transition. The hydrogen features are blue-shifted by ∼10 cm\sp−1 and broadened to a width of ∼30 cm\sp−1. Atomic helium features are similarly shifted and broadened. This effect is not caused by instrumental resolution. Three calculations based on the theory of excited states in liquid helium and semi-classical broadening theory are presented. The resulting line profiles of the first and second calculations are found to be in good agreement with the experimental observations. The third calculation is almost parameter free and reproduces the lineshift and linewidth within a factor of 2.

liquid helium, hydrogen-doped liquid helium, irradiation, 3 MeV proton beam, infrared spectroscopy