X-ray excited optical luminescence detection by scanning near-field optical microscope: a new tool for nanoscience.
Investigations of complex nanostructured materials used in modern technologies require special experimental techniques able to provide information on the structure and electronic properties of materials with a spatial resolution down to the nanometer scale. We tried to address these needs through the combination of x-ray absorption spectroscopy (XAS) using synchrotron radiation microbeams with scanning near-field optical microscopy (SNOM) detection of the x-ray excited optical luminescence (XEOL) signal. This new instrumentation offers the possibility to carry out a selective structural analysis of the sample surface with the subwavelength spatial resolution determined by the SNOM probe aperture. In addition, the apex of the optical fiber plays the role of a topographic probe, and chemical and topographic mappings can be simultaneously recorded. Our working XAS-SNOM prototype is based on a quartz tuning-fork head mounted on a high stability nanopositioning system; a coated optical fiber tip, operating as a probe in shear-force mode; a detection system coupled with the microscope head control system; and a dedicated software/hardware setup for synchronization of the XEOL signal detection with the synchrotron beamline acquisition system. We illustrate the possibility to obtain an element-specific contrast and to perform nano-XAS experiments by detecting the Zn K and W L(3) absorption edges in luminescent ZnO and mixed ZnWO(4)-ZnO nanostructured thin films.
Larcheri
Silvia
S
CNR-IFN, Istituto di Fotonica e Nanotecnologie, Unità FBK-CeFSA di Trento, Via alla Cascata 56/C, 38100 Trento, Italy.
Rocca
Francesco
F
Jandard
Frank
F
Pailharey
Daniel
D
Graziola
Roberto
R
Kuzmin
Alexei
A
Purans
Juris
J
D004867:Equipment Design; D019544:Equipment Failure Analysis; D008163:Luminescent Measurements / Q000295:instrumentation* / Q000379:methods; D020527:Microscopy, Scanning Probe / Q000295:instrumentation* / Q000379:methods; D036103:Nanotechnology / Q000295:instrumentation*; D055095:Optics and Photonics / Q000295:instrumentation*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013052:Spectrometry, X-Ray Emission / Q000295:instrumentation*; D018511:Systems Integration