Various doping levels of graphene on SiO₂/Si substrates are reported in the literature. We show by in situ Raman spectroscopy that the heating of chemical vapor deposited graphene on SiO₂/Si during the transfer process is the main factor causing this unintended doping of graphene samples. Large areas of graphene were analyzed using Raman spectroscopy, before and after the thermal treatment, to demonstrate that the effects of heating are spread throughout the graphene layer. The perturbations caused by the exposure of supported graphene during the first heating cycle (in vacuum) are irreversible, even though the samples were later in contact with the atmosphere. These results clarify deviations found in the Raman data obtained for transferred chemical vapor deposited graphene by different authors.

A novel and promising material, guanylurea(1+) hydrogen phosphite, which belongs to the group of inorganic salts of polarizable organic molecules was prepared. Its real potential for optical applications is based on the simplicity of synthesis, good ability to crystallize, transparency, thermal stability and efficiency of the second harmonic generation comparable to urea.