Some photoelectric properties of the nucleic acid bases in thin layers

The current-voltage characteristics of dark-conductivity and photoconductivity, the lux-ampere characteristics, the spectral dependence of photoconductivity and the relative quantum efficiency of vacuum deposited layers of adenine, thymine, uracil and cytosine were investigated at room temperature. The following values of photoconductivity thresholdE _th were obtained: 3·81 ±± 0·1 eV for adenine; 3·69±0·1 eV for thymine; 3·80±0·1 eV for uracil; 3·77 ± 0·1 eV for cytosine.It may be shown thatE _th is most probably the threshold value for intrinsic photoconductivity of NA bases and, consequently, corresponds to the first electron conductivity levelE _c or at leastE _c >E_th. The possible energy diagram of the NA bases is evaluated.