Table 1. The experimental ADEs and VDEs and the calculated VDEs for the four mononucleotides.

Mononucleotide	ADE*	VDE (experimental)	VDE (calculated)
dAMP-	5.55 ± 0.10	6.05 ± 0.50†	5.23
dCMP-	5.30 ± 0.10	5.80 ± 0.50†	5.24
dGMP-	4.61 ± 0.10	5.05 ± 0.10	4.90
dTMP-	5.40 ± 0.10	5.85 ± 0.50†	5.36

All energies are in eV.

^*The ADEs were measured by drawing a straight line along the leading edge of the threshold band and then adding a constant to the intersection with the binding energy axis to take into account the instrumental resolution at the given energy range.

^†Because of the lack of separated threshold band, the VDEs should be considered as rough estimates.