Marc Steinmetz Photography | The seven SI base units

MASS SPECTROMETRY
Elemental analysis for dissemination
of the mole at the PTB. Thermal
ionisation mass spectrometry allows
measuring the amount of a specific
element. The samples are thermally
ionized in the ion source (at front).
The ions are then accelerated,
sorted by a magnet and measured
by detectors. In back: heat-cleaning
of used sample holders in a vacuum
chamber for further use.

[mol] ‘The MOLE is the amount
of substance of a system which con-
tains as many elementary entities as
there are atoms in 0.012 kilogram
of carbon 12.
When the mole is used, the elemen-
tary entities must be specified and
may be atoms, molecules, ions, elec-
trons, other particles, or specified
groups of such particles.’