from The American Heritage® Dictionary of the English Language, 5th Edition.
- adjective Containing three atoms.
from The Century Dictionary.
- In chem.: Consisting of three atoms: applied to the molecules of elements where the atoms are of the same kind: as, a triatomic element; or to compounds where the atoms are unlike: as, triatomic molecules.
- Same as
- Having three hydroxyl groups by which other atoms or radicals may be attached without altering the structure of the rest of the molecule: thus, glycerin is called a triatomic alcohol.
from the GNU version of the Collaborative International Dictionary of English.
- adjective Having three atoms; -- said of certain elements or radicals.
- adjective Having a valence of three; trivalent; sometimes, in a specific sense, having three hydroxyl groups, whether acid or basic.
from Wiktionary, Creative Commons Attribution/Share-Alike License.
- adjective chemistry, of a molecule, etc. Consisting of three
Sorry, no etymologies found.
Since that's close to the thickness of ordinary glass, and since CO2, glass, and perspex block IR by the same mechanism, namely absorption by triatomic molecules, if not at the exact same wavelengths, the analogy is an excellent one even quantitatively!
Here is an infra-red absorption spectrum of a triatomic molecule.
Most of the living biomass is water, and this unique triatomic compound is also indispensable for all metabolic processes.
I am sitting in front of the racks controlling an ion beam of triatomic hydrogen.
This gave us much higher selectivity in observing certain molecules than the usual discharges, and we obtained almost pure fluorescence spectra of triatomic hydrogen.
After earning my PhD, I stayed at the Max-Planck Institute as a postdoc, working on laser excitation of Rydberg states of triatomic hydrogen and helium hydride.
It is worthy of notice that in diatomic elements _four_ funnels open on the faces of tetrahedra; in triatomic, _six_ funnels on the faces of cubes; in tetratomic, _eight_ funnels on the faces of octahedra.
The corresponding group consists of nitrogen, vanadium and niobium; they are triatomic, paramagnetic, and negative.
-- Boron, scandium and yttrium were examined; they are all triatomic, paramagnetic, and positive.
The corresponding group contains phosphorus, arsenic and antimony: bismuth also belongs to it, but was not examined; they are triatomic, diamagnetic and negative.