Sum frequency generation vibrational spectroscopy (SFG) has been applied to study two-dimensional (M) crystals formed by all isophthalic acid diester oil the surface of highly oriented pyrolytic graphite, providing complementary measurements to scanning tunneling microscopy (STM) and computational modeling. SFG results indicate that both aromatic and C=O groups in the 2D crystal till from the surface, This study demonstrates that a combination of SFG and STM techniques can be used to gain a more complete picture of 2D crystal Structure, and it is necessary to consider solvent-2D crystal interactions and dynamics in the computer models to achieve an accurate representation of interfacial structure.