Chemistry · the experiment
Count an energy in hertz
The simplest molecule, an energy given in kilohertz, a measurement now finer than the calculation. Four questions, from beginner to expert, on what the authors measure and on how they turn it into the energy that splits H₂.
1 · Say what is measured
Beginner
What do the experimenters measure directly?
2 · Convert an old uncertainty
From the values the paper gives side by side, 1 cm⁻¹ is about 29,980 MHz. In 2009, the collaboration gave the dissociation energy of H₂ within ±0.000 37 cm⁻¹.
Intermediate
What was that uncertainty in megahertz?
3 · Follow an error through the cycle
The paper's cycle: D₀(H₂) + Eᵢ(H) = Eᵢ(H₂) + D₀(H₂⁺). Eᵢ(H) and D₀(H₂⁺) are known to within 6 and 18 kHz.
Expert
If the measured ionization energy of H₂, Eᵢ(H₂), were 1 MHz too high, what would happen to the dissociation energy derived from it?
4 · Explain the choice of para-hydrogen
Expert
Why does the team measure para-hydrogen this time?
Bond measured
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