This study reports strong variations in the Raman spectra of single-layer graphene samples obtained by micromechanical cleavage, revealing the presence of excess charges, even in the absence of intentional doping. Doping concentrations up to ~10¹³ cm⁻² are estimated from the G peak shift and width, and the variation of both position and relative intensity of the second order 2D peak. Asymmetric G peaks indicate charge inhomogeneity on the scale of less than 1 µm. Graphene is a two-dimensional carbon system and a promising candidate for future electronics. Raman spectroscopy is a fast and non-destructive method for characterizing carbon materials. The G and D peaks in Raman spectra are common features in the 800-2000 cm⁻¹ region. The G peak corresponds to the E₂g phonon at the Brillouin zone center, while the D peak is due to the breathing modes of sp² atoms and requires a defect for its activation. The 2D peak, the second order of the D peak, is always seen, even when no D peak is present, since no defects are required for the activation of second order phonons. Its shape distinguishes single and multilayer samples. The ability to controllably dope n or p is key for applications. Raman spectroscopy can monitor doping in graphene. The effect of back gating and top gating on the G-peak position and its Full Width at Half Maximum (FWHM) was reported. Pos(G) increases and FWHM(G) decreases for both electron and hole doping. The stiffening of the G peak is due to the non-adiabatic removal of the Kohn-anomaly at Γ. The FWHM sharpening is due to blockage of the phonon decay into electron-hole pairs due to the Pauli exclusion principle. FWHM(G) sharpening saturates when doping causes a Fermi level shift bigger than half the phonon energy. This study shows that Raman spectroscopy can fingerprint differences between nominally identical samples. Even in the absence of a D peak, changes in the Raman parameters are most common and relate to the presence of excess charges. This is a significant finding, which reconciles the variation of electrical properties often found for nominally identical samples. Over 40 as-prepared monolayer graphenes were studied. These have different areas, from few µm² to 450 µm². Some of them are also measured in a device configuration, after deposition of Au electrodes. Over 100 spectra were measured with a 100X objective at 514 and 633 nm with a Renishaw spectrometer. The study shows that the maximum FWHM(G) for the most intrinsic samples is ~16 cm⁻¹, slightly higher than in graphite. This implies an inhomogeneous distribution of charges withinThis study reports strong variations in the Raman spectra of single-layer graphene samples obtained by micromechanical cleavage, revealing the presence of excess charges, even in the absence of intentional doping. Doping concentrations up to ~10¹³ cm⁻² are estimated from the G peak shift and width, and the variation of both position and relative intensity of the second order 2D peak. Asymmetric G peaks indicate charge inhomogeneity on the scale of less than 1 µm. Graphene is a two-dimensional carbon system and a promising candidate for future electronics. Raman spectroscopy is a fast and non-destructive method for characterizing carbon materials. The G and D peaks in Raman spectra are common features in the 800-2000 cm⁻¹ region. The G peak corresponds to the E₂g phonon at the Brillouin zone center, while the D peak is due to the breathing modes of sp² atoms and requires a defect for its activation. The 2D peak, the second order of the D peak, is always seen, even when no D peak is present, since no defects are required for the activation of second order phonons. Its shape distinguishes single and multilayer samples. The ability to controllably dope n or p is key for applications. Raman spectroscopy can monitor doping in graphene. The effect of back gating and top gating on the G-peak position and its Full Width at Half Maximum (FWHM) was reported. Pos(G) increases and FWHM(G) decreases for both electron and hole doping. The stiffening of the G peak is due to the non-adiabatic removal of the Kohn-anomaly at Γ. The FWHM sharpening is due to blockage of the phonon decay into electron-hole pairs due to the Pauli exclusion principle. FWHM(G) sharpening saturates when doping causes a Fermi level shift bigger than half the phonon energy. This study shows that Raman spectroscopy can fingerprint differences between nominally identical samples. Even in the absence of a D peak, changes in the Raman parameters are most common and relate to the presence of excess charges. This is a significant finding, which reconciles the variation of electrical properties often found for nominally identical samples. Over 40 as-prepared monolayer graphenes were studied. These have different areas, from few µm² to 450 µm². Some of them are also measured in a device configuration, after deposition of Au electrodes. Over 100 spectra were measured with a 100X objective at 514 and 633 nm with a Renishaw spectrometer. The study shows that the maximum FWHM(G) for the most intrinsic samples is ~16 cm⁻¹, slightly higher than in graphite. This implies an inhomogeneous distribution of charges within