Abstract
We report experiments in which the line shape of the Lyman-alpha () transition was measured for positronium (Ps) atoms both inside and outside a porous silica target. The energy interval for confined atoms was observed to be larger than that of free Ps by . A configuration interaction calculation yields results that are consistent with our sample, and suggests that decreases dramatically for larger cavity diameters. The linewidth of the transition, (FWHM), is about half of what one would expect for free Ps at room temperature due to the Dicke line narrowing effect of confinement. Such measurements can be used to determine void sizes in porous films and Ps dynamics therein, and elimination of the Doppler spread of atoms in a porous film could be useful for the efficient excitation of a Ps gas.
- Received 8 October 2010
DOI:https://doi.org/10.1103/PhysRevLett.106.023401
© 2011 The American Physical Society
Viewpoint
In tight spaces
Published 10 January 2011
Laser spectroscopy of positronium confined to nanoscale pores is a tool to probe the size of buried cavities and a step toward the long-term goal of a positronium BEC.
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