D

Doublet

Na D-line: 589.0 and 589.6 nm
Quick Reference
Formula / NotationNa D-line: 589.0 and 589.6 nm
Also Known AsSpectroscopic doublet, NMR doublet (d), spin-orbit doublet, fine-structure doublet

What is Doublet?

In spectroscopy, a doublet is a pair of closely spaced spectral lines arising from spin-orbit coupling or other splitting mechanisms. In NMR spectroscopy, a doublet occurs when a proton is coupled to one neighboring proton, resulting in two lines of equal intensity.

Formula & Notation

Na D-line: 589.0 and 589.6 nm

Other Names / Synonyms: Spectroscopic doublet, NMR doublet (d), spin-orbit doublet, fine-structure doublet

Properties & Characteristics

In spectroscopy, a doublet is a pair of closely spaced spectral lines arising from spin-orbit coupling in atoms (fine structure) or from coupling between equivalent nuclei in NMR. The sodium D-line doublet (589.0 and 589.6 nm) arises from the 3p→3s transition where the 3p level is split into ²P₃/₂ and ²P₁/₂ by spin-orbit interaction. In NMR, a doublet (d) occurs when one proton is split by one adjacent non-equivalent proton (n+1 rule).

Uses & Applications

Doublets in atomic spectroscopy are used to identify elements (sodium doublet in flame tests and AAS). NMR doublets identify the number of neighbouring protons in organic structure elucidation. Doublet splitting patterns are fundamental to ¹H and ¹³C NMR interpretation.

Safety Information

No direct safety concern for the concept. Spectroscopic instruments (UV lamps, laser sources, NMR magnets) have their own associated hazards: UV exposure, strong magnetic fields, cryogenic coolants. Follow instrument-specific safety guidelines.

Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.

Key Facts

Term Doublet
Formula Na D-line: 589.0 and 589.6 nm
Synonyms Spectroscopic doublet, NMR doublet (d), spin-orbit doublet, fine-structure doublet

Frequently Asked Questions

In spectroscopy, a doublet is a pair of closely spaced spectral lines arising from spin-orbit coupling or other splitting mechanisms. In NMR spectroscopy, a doublet occurs when a proton is coupled to one neighboring proton, resulting in two lines of equal intensity.

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