Photoisomerization of one double bond in a conjugated double bond system. It is a regular
E/Z photoisomerization.
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Compare with bicycle-pedal (BP) mechanism, hula-twist (HT) mechanism.
Source:
PAC, 2007, 79, 293. 'Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)' on page 377 (https://doi.org/10.1351/pac200779030293)