title: Why is the human visual system sensitive only to light of wavelengths from approximately 760 to 380 nm? An answer from thermochemistry and chemical kinetics.
abstract: The range of visible light has been explained by the knowledge available of gas-phase thermochemistry and chemical kinetics. The C, C-pi bond dissociation energy at the 11 and 12 positions of the rhodopsin complex is estimated to be approximately 37.4+/-1.5 kcal/mol. This energy is just equivalent to wavelength of the red limit of the visible light. The photons of the violet limit (approx. 75.2 kcal/mol) can break the weakest C-C and H-C bonds in important species involved in the photo-induced cis-trans isomerization cycle and can stop the visual cycle.
authors.affiliation: Molecular Energetics Consultants, St. Petersburg, FL 33701, USA.
authors.forename: Y R
authors.initials: YR
authors.lastname: Luo
mesh_terms: D006801:Humans; D007536:Isomerism; D007700:Kinetics; D008027:Light; D008956:Models, Chemical; D010775:Photic Stimulation; D020419:Photoreceptor Cells, Vertebrate / Q000737:chemistry / Q000502:physiology; D012172:Retinaldehyde / Q000737:chemistry / Q000502:physiology; D012243:Rhodopsin / Q000737:chemistry* / Q000502:physiology*; D013816:Thermodynamics; D014785:Vision, Ocular / Q000502:physiology*
chemical_list: D012243:Rhodopsin; D012172:Retinaldehyde