Strzelecka T
Physiol Chem Phys. 1982;14(3):219-22.
To determine a band model for synthetic melanin obtained by autooxidation of L-dopa (3,4-dihydroxyphenyl-L-alanine), dependence of dark current on temperature in the range 298-333 degrees K was measured as well as dependence of optical absorption coefficient on wave-length in the range 250-800 nm. It was found that up to 311 degrees K thermal activation energy equals 0.1 eV and above 313 degrees K it equals 0.78 eV. The first value is connected with the band of localized states at the Fermi level. Optical gap, determined from optical absorption measurements is equal to 1.40 eV. The estimated value of sigma o, assuming the value of thermal coefficient of activation-energy to be gamma = 5 X 10(-4) eV/degrees K, is 2 X 10(-6) omega -1 cm-1 for 0.1 eV and 5 X 10(2) omega -1 cm-1 for 0.78 eV. Density of states in the valence band is N(EV) = 8 X 10(21)/cm3 X eV, and in the band of localized states at the Fermi level N(EF) = 3 X 10(13)/cm3 X eV.
为了确定通过左旋多巴（3,4-二羟基苯丙氨酸）自氧化获得的合成黑色素的能带模型，测量了298 - 333开尔文温度范围内暗电流对温度的依赖性以及250 - 800纳米波长范围内光吸收系数对波长的依赖性。结果发现，在311开尔文以下热激活能等于0.1电子伏特，在313开尔文以上它等于0.78电子伏特。第一个值与费米能级处的局域态能带相关。由光吸收测量确定的光学带隙等于1.40电子伏特。假设热激活能的热系数值为γ = 5×10⁻⁴电子伏特/开尔文，对于0.1电子伏特，σₒ的估计值为2×10⁻⁶欧姆⁻¹厘米⁻¹，对于0.78电子伏特为5×10²欧姆⁻¹厘米⁻¹。价带中的态密度为N(EV) = 8×10²¹/厘米³×电子伏特，费米能级处局域态能带中的态密度为N(EF) = 3×10¹³/厘米³×电子伏特。
