10.1021/acs.jpclett.7b01377.s004 Hyunsoo Lee Hyunsoo Lee Jae-Hyeon Ko Jae-Hyeon Ko Jin Sik Choi Jin Sik Choi Jin Heui Hwang Jin Heui Hwang Yong-Hyun Kim Yong-Hyun Kim Miquel Salmeron Miquel Salmeron Jeong Young Park Jeong Young Park Enhancement of Friction by Water Intercalated between Graphene and Mica American Chemical Society 2017 theory calculations show vibration intercalated water graphene excitation Mica Common experience interface mica substrate energy transfer processes 2017-07-11 00:00:00 Media https://acs.figshare.com/articles/media/Enhancement_of_Friction_by_Water_Intercalated_between_Graphene_and_Mica/5209129 Common experience shows that friction converts mechanical energy into heat. The first part of this process is vibrational excitation of atoms at the interface between rubbing bodies. The second part is the removal of the vibration energy by transferring it from the interface to the substrate. However, it is difficult to disentangle the excitation and energy transfer processes. We solved this by using a system consisting of a SiO<sub>2</sub>-terminated tip sliding over graphene deposited on mica with intercalated water between them. The intercalated water was found to increase friction by a factor of ∼3 relative to dry mica. Density functional theory calculations show that water broadens the spectral range of graphene vibrationsparticularly the low-frequency flexural modesthus providing new excitation channels and also by increasing the overlap with the atomic vibrations of the mica substrate, which facilitates coupling and energy transfer.