Isotope effect in charge-transfer collisions of H with He<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mrow /><mml:mo>+</mml:mo></mml:msup></mml:math>
Physical review. A, Atomic, molecular, and optical physics/Physical review, A, Atomic, molecular, and optical physics