3D imaging of semiconductor colloid nanocrystals: on the way to nanodiagnostics of track membranes

Abstract

Abstract. The work concerns the feasibility of 3D optical diagnostic of porous media with subdifraction spatial resolution via epi-luminescence microscopy of single semiconductor colloid nanocrystals (quantum dots, QD) CdSe/ZnS used as emitting labels/nanoprobes. The nanoprecise reconstruction of axial coordinate is provided by double helix technique of point spread function transformation (DH-PSF). The results of QD localization in polycarbonate track membrane (TM) is presented.Track etched membranes are widely used in industry (high efficiency water filters) and science (metal nanostructure growing, optical analysis of DNA) [1]. However, the study of physical and chemical properties of such porous media is entangled due to the small sizes of pores (hundreds of nanometers and less). Thus methods of electronic microscopy have several restrictions, and probe microscopy (atomic-force microscopy) allows to only characterize the surface, giving no answer for the question of structure and properties of the pores' walls.In recent years the characterization of materials with complex structure and objects at nanometer scale by methods of super resolution optical microscopy with detection of single luminescence emitter-probes has become more and more popular ([2, 3] and links inside). The potential of such methods can be fulfilled in a nano diagnostics of complex polymer structures, and track membranes also. Moreover, the photophysical (spectral) characteristics of such probes are very sensitive to local environment, that can be used in future for characterization of that environment [2][3][4][5][6][7].Determination of all three spatial coordinates with nanometer precision is possible due to use of an idea of instrumental transformation of point spread function in double helix scheme using adaptive optics' phase transformation elements [8].The purpose of introduced work is development of methods of 3D laser spectromicroscopy of single colloid nanocrystals (quantum dots, QD) for nanodiagnostics of track etched membranes.