Bixin is an apocarotenoid found in annatto with 25 carbons with carboxylic acids at each end of the chain. It is an insoluble orange red pigment.

I am interested to study photon interaction with this molecule. Please, give me some head start on what to read. It is a red pigment, therefore it absorbs photons below 670 nm or so. How can I determine if this molecule allows luminescence in any degree? Electronic transitions? or just any refraction or scattering.

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    $\begingroup$ Wkikepedia has an article on this molecule, it is a derivative of a carotenoid. You should be able to find lots of data on these molecules , for example the pi-pi absorption transitions in these will be similar to that in Bixin. Usually these compounds are not luminescent to any great extent as non-radiative processes dominate. Often the cause is due to the lowest lying transition being symmetry forbidden . $\endgroup$
    – porphyrin
    Jun 21, 2017 at 7:01
  • $\begingroup$ You should add this as an answer . It was very helpful. $\endgroup$ Jun 24, 2017 at 0:56

1 Answer 1


In a first step I would widen the available search criteria. While accessing the English entry of wikipedia, collection of the chemical name, CAS number, smiles code (copy/paste), pubchem and chemspider ID are presented. These identifiers may become helpful in the subsequent searches in other databases. Nor would I hesitate (as long as my web browser allows proper display .and. there are at least some words barely understood in reading) to access the other versions (Spanish, Portuguese, ...), too.

In the public libraries of US' NIH, just the keyword "bixin" yields 150 (pmc) or 116 (pubmed) hits, that after some narrowing yield entries like this abstract in Spectrochimica Acta or this about triplet states of bixin, published in J. Agric. Food Chem.

While the British chemspider does not yield spectra directly, the literature references listed by this database include even surprising finds like doi 10.1039/C4CS00309H (2015ChemSocRev3244) about Vegetable-based dye-sensitized solar cells.

Do not omit collections like researchgate, as here, or figshare. If your institute has subscriber access, chemical databases like Reaxys (Elsevier) or Scifinder Scholar (ACS) may indicate primary literature including spectroscopic data, too. No longer chemistry/physics centred, a search in Thomson Reuters' Web of Science, and more engineering-oriented Scopus (by Elsevier) may round the picture.


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