Precision microwave measurement of the 2(3)P(1)-2(3)P(0) interval in atomic helium: a determination of the fine-structure constant.
The 2(3)P(1)-to- 2(3)P(0) interval in atomic helium is measured using a thermal beam of metastable helium atoms excited to the 2(3)P state using a 1.08-microm diode laser. The 2(3)P(1)-to- 2(3)P(0) transition is driven by 29.6-GHz microwaves in a rectangular waveguide cavity. Our result of 29,616,950.9+/-0.9 kHz is the most precise measurement of helium 2(3)P fine structure. When compared to precise theory for this interval, this measurement leads to a determination of the fine-structure constant of 1/137.0359864(31).
George
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Department of Physics, York University, 4700 Keele Street, Toronto, Ontario, Canada M3J 1P3.
Lombardi
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Hessels
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