integration variable instead of y$_{1}$ , we obtain short arcs, so that ϕ$_{1}$ ≪ 1 and | 2 p − q | ≪ p . Thus, we ex- pand the exponent to ϕ 3 $_{1}$, while in the prefactor we keep the leading term at ϕ$_{1}$ → 0. In the experiment described in the paper, the excitation and detection are unpolar- ized, so we simply omit the the expression in the square brackets, which describes the polarization dependence. Denoting Rϕ$_{1}$ = z , we arrive at The first integration is simply R cos ϕ$_{1}$ dϕ$_{1}$ = dy$_{1}$ , the factor √$_{R}$$_{tan}$$_{ϕ}$$_{1}$$_{/}$$_{sin 2}$$_{ϕ}$$_{1}$ comes from the gaussian inte- gration, and the cosines give the angular dependence of the electron-photon [cos( ϕ$_{in}$$_{,}$$_{out}$ − ϕ )] and electron-phonon (cos ϕ$_{1}$ ) matrix elements. Integration over ϕ gives which is Eq. (1) of the main text. The integral is calcu- lated using the relations 33,39 M ( q ) ∝ π/ 2 ∫ 0 R cos ϕ$_{1}$ dϕ$_{1}$ ϕ$_{1}$ ∫ − ϕ$_{1}$ dϕ √$_{R}$$_{tan}$$_{ϕ}$$_{1}$ sin 2 ϕ$_{1}$ × × e 2 ipR ( ϕ$_{1}$ +sin ϕ$_{1}$ cos ϕ$_{1}$ ) − 2 iqR sin ϕ$_{1}$ − 4 γRϕ$_{1}$/v × cos 2 ϕ$_{1}$ cos( ϕ$_{in}$ − ϕ ) cos( ϕ$_{out}$ − ϕ ) . (A40) M ( q ) ∝ ∞ ∫ 0 dz √$_{z e}$ − [ i ( q − 2 p )+2 γ/v ] z − i [ p/ (12 R $^{2}$)] z $^{3}$, (A42) 1 2 π 3 / 2 ∞ ∫ 0 dt √$_{t}$ cos ( xt + t 3 12 + π 4 ) = Ai $^{2}$( x ) , (A43) 1 2 π 3 / 2 ∞ ∫ 0 dt √$_{t}$ sin ( xt + t 3 12 + π 4 ) = Ai( x ) Bi( x ) . (A44) M ( q ) ∝ π/ 2 ∫ 0 R 3 / 2 dϕ$_{1}$ √ sin ϕ$_{1}$ cos 3 ϕ$_{1}$ × × e 2 ipR ( ϕ$_{1}$ +sin ϕ$_{1}$ cos ϕ$_{1}$ ) − 2 iqR sin ϕ$_{1}$ − 4 γRϕ$_{1}$/v × × [ cos( ϕ$_{in}$ − ϕ$_{out}$ ) (sin ϕ$_{1}$ ) /ϕ$_{1}$ + cos ϕ$_{1}$ cos( ϕ$_{in}$ + ϕ$_{out}$ ) ] . (A41) Taking advantage of the limit γR/v ≫ 1, we can focus on 10 26 J. Yan, Y. Zhang, P. Kim, and A. Pinczuk, Phys. Rev. Lett. 98 , 166802, (2007). 25 S. Pisana, M. Lazzeri, C. Casiraghi, K.S. Novoselov, A.K. Geim, A.C. Ferrari, and F. Mauri, Nature Mat. 6 , 198, (2007). 24 A. Das, B. Chakraborty, S. Piscanec, S. Pisana, A.K. Sood, and A.C. Ferrari, Phys. Rev. B 79 , 155417, (2009). 23 A. Das, S. Pisana, B. Chakraborty, S. Piscanec, S.K. Saha, U.V. Waghmare, K.S. Novoselov, H.R. Krishnamurthy, A.K. Geim, A.C. Ferrari, and A.K. Sood, Nature Nan- otech. 3 , 210, (2008). 22 J.A. Robinson, C.P. Puls, N.E. Staley, J.P. Stitt, M.A. Fanton, K.V. Emtsev, T. Seyller, and Y. Liu, Nano Lett. 9 , 964, (2009). 14 J. Hass, F. Varchon, J.E. Millan-Otoya, M. Sprinkle, N. Sharma, W.A. de Heer, , P.N. First, L. Magaud, and 13 D.L. Mafra, G. Samsonidze, L.M. Malard, D.C. Elias, J.C. Brant, F. Plentz, E.S. Alves, and M.A. Pimenta, Phys. Rev. B 76 , 233407, (2009). 12 R. Saito, A. Jorio, A.G. Souza Filho, G. Dresselhaus, M.S. Dresselhaus, and M.A. Pimenta, Phys. Rev. Lett. 88 , 027401, (2002). 11 D.M. Basko, Phys. Rev. B 76 , 081405(R), (2007). 10 J. K¨ urti, V. Z´ olyomi, A. Gr¨ uneis, and H. Kuzmany, Phys. Rev. B 65 , 165433, (2002). 9 C. Thomsen, and S. Reich, Phys. Rev. Lett 85 , 5214, (2000). 8 A.V. Baranov, A.N. Bekhterev, Y.S. Bobovich, and V.I. Petrov, Opt. Spektrosk. 62 , 1036, (1987). 7 C. Faugeras, A. Nerri`ere, M. Potemski, A. Mahmood, E. Dujardin, C. Berger, and W.A. de Heer, Appl. Phys. Lett. 92 , 011914, (2008). 6 D. Graf, F. Molitor, K. Ensslin, C. Stampfer, A. Jungen, C. Hierold, and L. Wirtz, NanoLett. 7 , 238, (2007). 5 A.C. Ferrari, J.C. Meyer, V. Scardaci, C. Casir- aghi, M. Lazzeri, F. Mauri, S. Piscanec, D. Jiang, K.S. Novoselov, S. Roth, and A.K. Geim, Phys. Rev. Lett. 97 , 187401, (2006). 4 P.N. Sutter, J.I. Flege, and E.A. Sutter, Nature Mat. 7 , 406, (2008). 3 C. Berger, Z. Song, Z. Li, X. Li, A.Y. Ogbazghi, R. Feng, Z. Dai, A.N. Marchenko, E.H. Conrad, P.N. First, and W.A. de Heer, J. Phys. Chem. 108 , 19912, (2004). 2 K.S. Novoselov, D. Jiang, F. Schedin, T.J. Booth, V.V. Khotkevich, S.V. Morozov, and A.K. Geim, PNAS 102 , 10451, (2005). 1 A.K. Geim, and K.S. Novoselov, Nature Mat. 6 , 183, (2007) 21 P. Poncharal, A. Ayari, T. Michel, and J.-L Sauvajol, Phys. Rev. B 78 , 113407, (2008). 20 Z. Ni, Y. Wang, T. Yu, Y. You, and Z. Shen, Phys. Rev. B 77 , 235403, (2008). 19 M. Orlita, C. Faugeras, P. Plochocka, P. Neugebauer, G. Martinez, D.K. Maude, A.-L Barra, M. Sprinkle, C. Berger, W.A. de Heer, and M. Potemski, Phys. Rev. Lett. 101 , 267601, (2008). 18 C. Faugeras, M. Amado, P. Kossacki, M. Orlita, M. Sprin- kle, C. Berger, W.A. de Heer, and M. Potemski, Phys. Rev. Lett. 103 , 186803, (2009). 17 D.L. Miller, K.E. Kubista, G.M. Rutter, M. Ruan, W.A. de Heer, P.N. First, and J.A. Stroscio, Science 324 , 924, (2009). 16 M.L. Sadowski, G. Martinez, M. Potemski, C. Berger, and W.A. de Heer, Phys. Rev. Lett. 97 , 266405, (2006). 15 C. Berger, Z. Song, X. Li, X. Wu, N. Brown, C. Naud, D. Mayou, T. Li, J. Hass, A.N. Marchenkov, E.H. Conrad, P.N. First, and W.A. de Heer, Science 312 , 1191, (2006). E.H. Conrad, Phys. Rev. Lett. 100 , 125504, (2008).