Electronic structure of genomic DNA: a photoemission and X-ray absorption study.

The electronic structure of genomic DNA has been comprehensively characterized by synchrotron-based X-ray absorption and X-ray photoelectron spectroscopy. Both unoccupied and occupied states close to the Fermi level have been unveiled and attributed to particular sites within the DNA structure. A semiconductor-like electronic structure with a band gap of approximately 2.6 eV has been found at which the pi and pi* orbitals of the nucleobase stack make major contributions to the highest occupied and lowest unoccupied molecular orbitals, respectively, in agreement with previous theoretical predictions.