Table 2.

Relative peak intensity of the XPS C(1s) lines at the given binding energies for A, C, G, T, U powders from ref. 16 and for the corresponding XPS C(1s) observed from formamide on TiO₂ (001) surface

	Relative intensity,* a.u.
Energy, eV	A	C	G	T	U	Attribution	300 K†	450 K†	600 K†	700 K†
285	6	13	9	14	10	C-H; C-C	9	9	8	8
286-287	13	11	12	7	8	C-Nx	12	13	11	8
288	0	13	11	6	3	Amide	51	46	46	24
289-290	0	6	0	7	13	Urea	22	24	20	15
>290							28	24	25	17

A, adenine; C, cytosine; G, guanine; T, thymine; U, uracil; a.u., arbitrary units.

^*Calculated from ref. 16.

^†Calculated from Fig. 2c.