Free Dangling Bond Electrons in Graphonyx Materials
Sharp peak observed (from spins in dangling bonds): peak to peak width ~ 4 Gauss Spin concentration: 7.8 mmol/cm3 g values is 2.0023 which is same with free electron-spin value (2.0023)
Notes from National High Magnetic Field Laboratory Analysis, Florida State University ( Seven Samples Submitted)
We only observed signals from sample #1, #4 and #6. The major peaks of all three samples have g factors close to free electron g value - 2.0023, which indicates that the signals are from free electrons, such as dangling bonds, but not from transition metal impurities. The g values of #1, #4 and #6 are 2.0023, 2.0025, and 2.0044, respectively. The slight shift of g values between samples indicates that the free electron environment has changed for different samples, suggesting that local bond environments have changed.
Sample #1: The spectra of sample 1 show a sharp peak. The peak to peak line width (Hpp) is ~ 4G. According to the reference you sent me, this peak could come from spins in dangling bonds. The spin concentration for this sample is ~7.8 mmol/cm3.
Sample #4: The spectra of sample 4 show a moderate broad peak. The peak to peak line width (Hpp) is ~ 12G. This peak could be similar to either #1 or #6, a mixture, or other type of bonds. The spin concentration for this sample is ~ 0.6 mmol/cm3
Sample #6: The spectra of sample 6 show a broad peak. The peak to peak line width (Hpp) is ~ 25G. This peak could come from π electron spins. The spin concentration for this sample is ~ 0.5 mmol/cm3. Also, metal contamination is observed for this sample, most likely Mn. Mn is everywhere, such as in tap water.
Possible reasons for no signal from other 4 samples:
1). The number of free electron spins is too low to be detected by EPR.
2). No free electron spins.