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Whiteboard Notes on measuring the concentration of deuterium.
- Electronics companies selling overseas now often seem to have a US export requirement loosely worded that the goods are not to be used in the enrichment of deuterium.
- Wide lines.
- Instrumentation not easy to self build.
- Potentially the same information as Infra Red.
- Water does not couple well to Raman, normally this is an advantage and vibrational information for organic molecules can be obtained in aq. solution.
- Earth field NMR should work.
- For an earth field lamor of ~2khz for H-1, H-2 would be ~307Hz
- H-2 is ~100 times less detectable than H-1 on a molar basis
- H-2 is quadropolar, line will be broader
Starting with a regular earth field design or the N. Wadsworth magnetometer from scientific american. See also the magnetometer at Hackaday.io Altering the filter or boosting the local field should allow us to see the deuterium signal. This will be weak. Earth field inside most houses may blur the signal a lot, this will not mix the signals but it may bury the peaks in the noise floor. Deuterium signal of ordinary water will be very weak and may not be detectable by this method in reasonable time. Are shim coils worthwhile in a domestic setting or do line power fields dominate?
Home made mass spec probably not feasible. Easiest ions to separate but fusor level complexity of vacuum system, electronics, ion source and focusing. TOF mass spec with spark would probably be easiest but the vacuum system is a major project on it's own.
Optical vis methods.
The atomic lines of deuterium are shifted from protium. The effect is small (around 0.2nm at 656nm) but the atomic lines are narrow anyway. A grating spectrometer might be difficult. Fabry-Perot interferometer may work, it's certainly feasible to build at home. HeNe mirrors may work usually they are a plane mirror and a concave, 2 concaves together would give us a shorter cavity and might reach the spectral range we require. Even HeNe output mirrors are really good so this may still have a high Q. If HeNe mirrors are not suitable then we may be waiting for dye laser mirrors which are scarce. Filters would be needed to remove all other lines or a crude monochromator. What degree of line broadening would be tolerable?
Optical avoiding spectroscopy
So long as line broadening is not a problem we may be able to solve this with 3 discharge lamps and an optical chopper. One containing protium gas, another deuterium and the third the gas under measurement. By measuring the absorbance of the P and D signals that should tell us the amount of P and D in the unknown discharge.