Chemistry · the experiment
Weigh the product of a single ion
One calcium ion, one water ion and HD gas at 5.4 kelvin. Find which product formed, correct the count for the impurity, then compare it with the simulations.
1 · Find the product
The team shakes the pair at 531.9 kHz: as long as the water ion has not reacted, the calcium's image is blurred.
Beginner
Why does the calcium's image sharpen again when the water ion reacts?
The ion has just reacted. The pair's frequencies (the article's table): 531.9 kHz with H₂O⁺, 529.2 with H₃O⁺, 526.4 with H₂DO⁺. Set the excitation frequency until the calcium's image blurs.
2 · Correct the count
Over 16 days, 441 reactions: 271 H₃O⁺ and 170 H₂DO⁺.
Intermediate
What is the raw H₃O⁺ / H₂DO⁺ ratio?
The corrected ratio removes the share α of reactions expected with H₂ (which reacts 1.19 times faster than HD). Set the share of H₂ in the gas until you get back the published ratio, 1.50, to within 0.01.
3 · Match the simulations
Expert
What can you conclude about the gap between 1.50 and 1.15?
The simulations give 1.15. Raise the share of H₂ until the corrected ratio comes down to 1.15, to within 0.01.
4 · Caught in a well
In the simulations at about 10 kelvin, among the collisions that got trapped, the ratio drops from 1.35 for the shortest stays to 1.21 for the longest.
Expert
Why does a complex that lives longer favour hydrogen less?
Product weighed
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