Molecular dynamics simulation was used to study the ionic liquid（IL） crystalline film based on 1-ethyl-3-methylimidazolium bis[trifluoromethylsulfonyl]imide（[emim][Tf2N]） and 1-ethyl-3-methylimidazolium trifluorom...Molecular dynamics simulation was used to study the ionic liquid（IL） crystalline film based on 1-ethyl-3-methylimidazolium bis[trifluoromethylsulfonyl]imide（[emim][Tf2N]） and 1-ethyl-3-methylimidazolium trifluoromethanesulfonate（[emim][TfO]） on the graphite surface. Our results show that the cations are parallelly dis- tributed to the surface in the 1/2 monolayer（ML） crystalline film. The [Tf2N] anions are parallel to the surface with the oxygen atoms at the bottom, whereas the [TfO]- anions are perpendicularly distributed to the surface also with the oxygen atoms at the bottom in the 1/2 ML crystalline film. It has been found that the IL-vapor interface strongly in- fluences the arrangement of ions at the interface. The anions in the top layer with the oxygen atoms outmost turn over to make themselves with the F atoms outmost so as to form C--H...O hydrogen bonds with the cations. The calcu- lated orientational ordering shows that in the outmost layer at the IL-vapor interface, the cation rings present either oarallel or oernendicular to the surface at 350 K.展开更多
文摘Molecular dynamics simulation was used to study the ionic liquid（IL） crystalline film based on 1-ethyl-3-methylimidazolium bis[trifluoromethylsulfonyl]imide（[emim][Tf2N]） and 1-ethyl-3-methylimidazolium trifluoromethanesulfonate（[emim][TfO]） on the graphite surface. Our results show that the cations are parallelly dis- tributed to the surface in the 1/2 monolayer（ML） crystalline film. The [Tf2N] anions are parallel to the surface with the oxygen atoms at the bottom, whereas the [TfO]- anions are perpendicularly distributed to the surface also with the oxygen atoms at the bottom in the 1/2 ML crystalline film. It has been found that the IL-vapor interface strongly in- fluences the arrangement of ions at the interface. The anions in the top layer with the oxygen atoms outmost turn over to make themselves with the F atoms outmost so as to form C--H...O hydrogen bonds with the cations. The calcu- lated orientational ordering shows that in the outmost layer at the IL-vapor interface, the cation rings present either oarallel or oernendicular to the surface at 350 K.
