User Tools

    To create and edit articles, please register and log-in

Main Menu : categories & index etc.

Main menu
Click categories to expand

A-Z listingplugin-autotooltip__plain plugin-autotooltip_bigA-Z listing

This is an alphabetical index of all content pages.

Other categories



Also see

Importance Ratings
Curator's rationale
AI Policy

Twitter feed 𝕏

Feeds + s.e.o. etc.
rss / xml feed
sitemap file
A-Z listing (archived)

Indexed under : Chemistry

Wikenigma - an Encyclopedia of Unknowns Wikenigma - an Encyclopedia of the Unknown


Photo-isomerization is the name given to the structural re-arrangement of asymmetric chemical compound molecules from one 'isomer' (e.g. 'left-handed' or 'right handed') to another, when illuminated.

The process is normally reversible, is dependent on the wavelength ('colour') of the light, and is extremely rapid, in the order of picoseconds.

Examples include relatively simple organic chemicals such as stilbene and azobenzene - and also more complicated compounds such as retinal, which is responsible for the detection of light in animal eyes.

The isomer-flipping is widely used in various chemical production processes, and in 'writable' digital optical media etc.

Other than the observation that the energy of the photons somehow flips the molecules, there is currently no exact description of the physical process behind the light-induced changes - even for the simplest chemicals ( See : J. Phys. Chem. A 2004, 108, 6, 950–95

Editor's note : This article has been given a 3 star importance rating. Without the as-yet-unexplained light-induced isomer flips of Retinal, you would not be reading this.

Importance Rating

    Please share this page to help promote Wikenigma !

Dear reader : Do you have any suggestions for the site's content?

Ideas for new topics, and suggested additions / corrections for older ones, are always welcome.

If you have skills or interests in a particular field, and have suggestions for Wikenigma, get in touch !

Or, if you'd like to become a regular contributor . . . request a login password. Registered users can edit the entire content of the site, and also create new pages.

( The 'Notes for contributors' section in the main menu has further information and guidelines etc.)

Automatic Translation

You are currently viewing an auto-translated version of Wikenigma

Please be aware that no automatic translation engines are 100% accurate, and so the auto-translated content will very probably feature errors and omissions.

Nevertheless, Wikenigma hopes that the translated content will help to attract a wider global audience.

Show another (random) article

Further resources :