Why Does Diamond Absorb Infra-Red Radiation?

Diamond‐based DNA sensors: surface functionalization and read‐out strategies

“…Sub-type II-a is very pure, transparent diamond. All diamond, even type II-a, absorbs in the IR due to phonon processes [96]. One allowed (twophonon) process is the destruction of one phonon of 335 cm -1 and the creation of a second one of 1275 cm -1 .…”

“…They give rise to the absorption of diamond in the IR range between 4000 cm -1 to 1500 cm -1 (= 2.5 µm to 6.7 µm). The temperature dependence of this absorption has been studied in detail by Davies et al [96]. For thin diamond windows and for low temperatures, the absorption is still reasonably low at the 10.6 µm (934 cm -1 ) CO 2 -laser line [96].…”

“…The temperature dependence of this absorption has been studied in detail by Davies et al [96]. For thin diamond windows and for low temperatures, the absorption is still reasonably low at the 10.6 µm (934 cm -1 ) CO 2 -laser line [96]. IR photon absorption with the creation of only one phonon is forbidden by the inversion symmetry of the perfect diamond structure.…”

Far-infrared photon absorption by phonons in ZnTe crystals

“…Moreover, it is not clear to what extent this rule holds for photon-phonon interactions. Four decades have passed since it was said [11] that understanding the light-lattice interaction was in its infancy and in spite of the recent theoretical developments [10,13] it is still far from maturity.…”

“…Apart from the transverse optical (TO) mode resonance, intriguing absorption bands have been observed in the far-infrared (THz) range [1], not attributable to the TO oscillation inharmonism [2]. It has become evident that electric dipoles induced by light waves involve combinations of two or more lattice modes [2][3][4][5][6][7][8][9][10]. Subsidiary absorption has been found even in non-ionic crystals [2,3,8,9], where the TO mode resonance is absent.…”