The arrangement of carbon atoms in graphene is the same as that of graphite monoatomic layer, which has the following characteristics: carbon atoms have four valence electrons, three of which generate sp2 bonds, that is, each carbon atom contributes an unbound electron on the pz orbit, and the pz orbit of adjacent atoms is perpendicular to the plane to form π bonds, and the newly formed π bonds are in a semi-filled state.
It is confirmed that the coordination number of carbon atoms in graphene is 3, the bond length between every two adjacent carbon atoms is1.42×10-10 m, and the included angle between bonds is 120.
In addition to the honeycomb layered structure in which σ bonds are connected with other carbon atoms to form hexagonal rings, the pz orbital of each carbon atom perpendicular to the layer plane can form a large π bond of polyatomic atoms (similar to benzene rings) throughout the whole layer, so it has excellent electrical conductivity and optical properties.
Extended data
When the incident light intensity exceeds a certain critical value, the absorption of graphene will reach saturation. These characteristics enable graphene to be used as a passive mode-locked laser.
When the input light intensity exceeds the threshold, this unique absorption may become saturated, which is called saturation effect. Graphene can be saturated and easily excited in the near infrared region due to global light absorption and zero band gap. Because of this special property, graphene is widely used in ultrafast photonics. The optical response of the graphene/graphene oxide layer can be electrically tuned.
Under stronger laser irradiation, graphene has nonlinear optical Kerr effect and nonlinear phase shift.
Solubility: it shows good solubility in nonpolar solvents, and has super hydrophobicity and super lipophilicity.
Melting point: in the study of 20 15, scientists said it was about 4 125K, and other studies said it was about 5000K.
Other characteristics: it can adsorb and desorb various atoms and molecules.