Double-resonant LA phonon scattering in defective graphene and carbon nanotubes

Abstract

We present measurements of the D Raman mode in graphene and carbon nanotubes at different laser excitation energies. The Raman mode around 1050 -1150 cm −1 originates from a doubleresonant scattering process of longitudinal acoustic (LA) phonons with defects. We investigate its dependence on laser excitation energy, on the number of graphene layers and on the carbon nanotube diameter. We assign this Raman mode to so-called 'inner' processes with resonant phonons mainly from the Γ−K high-symmetry direction. The asymmetry of the D mode is explained by additional contributions from phonons next to the Γ − K line. Our results demonstrate the importance of inner contributions in the double-resonance scattering process and add a fast method to investigate acoustic phonons in graphene and carbon nanotubes by optical spectroscopy.

Raman Spectroscopic Study of As-Deposited and Exfoliated Defected Graphene Grown on (001) Si Substrates by CVD

“…The flakes have very similar surface morphology to those transferred on SiO 2 /Si substrates (Figure 1(d)). The Raman spectrum of such flakes is not significantly different from that of the as-deposited layers ( Figure 7); however, the D" band appears at 1096 (for 488 nm excitation) and at 1135 cm −1 (for 633 nm excitation), respectively, that is, they coincide with the data of Herziger et al [14].…”

“…is resulting from double-resonance intervalley scattering of LA phonons on defects (see [14]). The intensity of this band should be about 100 times lower than that of the D band.…”

Electrochemically Exfoliated Graphene-Like Nanosheets for Use in Ceramic Nanocomposites

“…These bands are detected in Figure 2 a as a peak that overlaps with the left side of the D band and as a shoulder on the right side of the G peak, respectively. While the latter has been named in most of the published works as D’, the former has been named as T 1 [ 33 ], D 4 [ 34 ], D* [ 23 , 27 , 35 ] or D’’ [ 29 , 30 , 36 ] depending on the authors and on the studied carbon-based material. Moreover, a broad shoulder between the D and G peaks can also be seen in Figure 2 a.…”

Tunable quantum interference in bilayer graphene in double-resonant Raman scattering

“…Holes in the substrate were fabricated by reactive ion etching (RIE), exhibiting a diameter of 3 µm and depth of approximately 8 µm. Defective bilayer graphene samples were prepared by swift heavy ion irradiation (Xe 26+ , 91 MeV) [22,23] at normal incidence using different ion fluxes [12].…”