Surfaces and orientations: much to fret about?
  Single molecule FRET (fluorescence resonance energy transfer) is a powerful technique for detecting real-time conformational changes and molecular interactions during biological reactions. In this review, we examine different techniques of extending observation times via immobilization and illustrate how useful biological information can be obtained from single molecule FRET time trajectories with or without absolute distance information. 
Ivan Rasnik, Sean A. McKinney and Taekjip Ha