抄録
We calculated the energy states of electrons of voltage sensitive dye WW781 by molecular orbital method, and investigated the mechanism of optical spectrum shifts due to membrane potential. The absorption and fluorescence emission spectrum may undergo an electrochromic shift in a membrane in which electric field is caused by action potentials, so we investigated the change in the absorption and fluorescence characteristics of the dye in the presence of the electric field. The absorption energy was calculated at 2.063[eV] and it is equivalent to the energy of 601[nm] light. This calculation result agrees well with the absorption peak at 608[nm] in methanol solution. Assuming that the membrane has 100[Å] in thickness and change in an action potential is 100[mV], the change in the magnitude of electric field is 107[V/m], In this field the shift of absorption spectrum was calculated at 0.13[nm]. This result indicates that the absorption spectrum shift of the dye depends on the electric field due to action potentials.
