Energy Transfer
Energy Transfer ➢ Once light energy (quanta) is absorbed, as the edrops back to ground state, the energy can be: • Lost as heat. • Lost as light (fluorescence) at slightly lower wavelength + a little heat. • Transferred to another molecule by exciting the other molecule’s e-. • Transferred to another molecule by passing the excited e- itself. ➢ The last two can be used in photochemical reactions powering photosynthesis
Light -Properties Photons can be absorbed by atoms to excite electrons(e)into higher energy states, or dislodge e from atoms Photon ucleus Electron Ground state Excited state
Fluorescence (B) Higher excited state 400 Blue Heat loss 500 Lowest excited state 6005 Red 700 Fluorescence Fluorescence Absorption 800 90 Ground state 武YT的四C
Fluorescence
Carotenoids Energy lost Chlorophyll b* as heat urng excitation Chlorophyll a transfer P680 Energy of reaction center excited state available for storage Ground-state energy
Energy transfer Electron transfer Light Pigment molecules Acceptor Reaction center Antenna complex Donor