Metastable states of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msup><mml:mrow><mml:mi>Si</mml:mi></mml:mrow><mml:mo>−</mml:mo></mml:msup></mml:math> observed in a cryogenic storage ring
Physical review. A/Physical review, A