Recently

the long period X-ray standing wave method has been developed as astructure probe for atom layers in thin solid or liquid films.Formation and characteristics of the long period X-ray standing wave field are described and the physical model is demonstrated for its applications.With the advanced synchrotron radiation source

this method reaches a detection range of ～100nm

a space resolution of～0.1nm and a sensitivity of ～10 12 atom/cm 2

and shows itself as a new ypowerful tool for investigating membrane-protein and charged surface-solution interactions and structure characterizations.