|
Direct correlation of SPM (Scanning Probe Microscopy) techniques with
Raman scattering was a dream…now its a reality. The combined Nanonics MultiView/Renishaw inVia Raman Microscope systems are the first systems to allow true on-line SPM with Raman imaging
Features
•Combined on-line pixel by pixel surface topography and chemical characterization via Raman spectroscopy at ultrahigh resolution.
•Tip enhancement Raman spectroscopy (TERS) with metallic coated AFM tips.
•AFM and Raman spectroscopy of MEMS devices. High resolution of local silicon stress in MEMS devices.
•Fully integrated with upright and inverted microscopes through the use of transparent cantilevered bent tips and a 3D Flat scanner.
•Significant resolution improvement due to topography-corrected focus through height adjustment via online AFM feedback
•Hardware and software solutions for Raman correlated mapping through “collage” maps, intensity maps, band position maps, measurement and analysis of correlated near field and far field spectra (2 points measurement), tip and sample scanning combinations.
•Multiple probe option of Raman interfered probe (tip enhancement, nano indentation, force regulation and high resolution AFM probe.
Unique Applications
 |
The image (left) is a combined AFM topographic image with Raman map of a graphite-diamond film. The 3D surface shows the topography variations and the colours indicate the Raman Intensity of the 1331cm^-1 band. Raman spectra have been collected simultaneously with the topographic data through an AFM scan. Surface theory of this film predicts that the diamond grow in the topographical valleys. The collage image shows higher intensities of the diamond band (1331cm^-1) in the valleys as predicated. |
SPM and Raman Integration
The hardware and the software of the Nanonics NSOM/AFM MultiView systems are transparently integrated with a Renishaw Raman Microscope
There are two major factors that enable the Nanonics AFM system to be successfully integrated with Raman spectroscopy:
1) Nanonics' patented, transparent, glass cantilevered probes
2) Nanonics' flat and ultrathin scanning platform that makes use of four piezo drivers. These cylindrical piezos are placed in a quadrant fashion around the sacnner.
Nanonics' Unique Probes
|
|
Probe geometry:
Nanonics systems use patented cantilevered optical fiber probes. The cantilevered optical fiber is held between the objective lens and the sample without obstructing any aspect of the far-field conventional upright or inverted microscope. The tip of the fiber is exposed, allowing direct viewing of the scanned region. The probe geometry and dimensions can be easily customised for different applications
|
 |
Advantage over standard silicon probes:
•These probes overcome the problem of obscuring the far filed view of the upright microscope. Standard silicon tips have a flat cantilever which blocks the field of view from an upright microscope
•Does not generate any background Raman signal unlike regular silicon probe.
•Easily customized to different samples and applications
Taking advantage of the points above, There are NO LIMITATIONS on Samples, both opaque and transparent samples can be used with out any interference with the Raman data.
|
3D FlatScanner Platform
 |
Flat Scanner:
Nanonics SPM platforms are optically and micro-Raman friendly. The platforms make use of four cylindrical piezos placed around the platform in a quadrant fashion (as shown in Fig.4). As opposed to upright-architectured piezos used in conventional SPM (see fig.?) platforms, the Nanonics scanning stage is very thin (7mm) allowing the head to be integrated into all upright optical microscopes. The open optical axis allows for free viewing of >20mm.The platform also allows for rough scanning whereby the sample under inspection can be rapidly moved via inertial motion mechanism. |
 |
Advantages of the flat scanner:
•Free optical axis for upright and inverted optical microscope view.
•Scanning small and large topography due to the flexible scan ranges from nanometer scale to approximately 100 microns in XY and up to 70 microns in Z.
•Sample fine positioning through inertial motion in increments of 1 micron up to 2-3mm.
|
Topographical and Chemical Characterisation- Data Correlation
For achieving AFM Raman combined data, the tip is adjusted to the center of the far field Raman illumination laser spot, the area of interest on the sample is brought to that point (by inertial motion), AFM parameters are defined, points for Raman measurement are defined relative to the AFM scan parameters, Raman settings are selected, running the scan, AFM imaging in progress, Raman spectra are acquired within the defined pixels during the AFM scan, scan is completed.
Raman map images can be created in different types such as mapping the intensity of a specific band at the different points or mapping a band shift in wave numbers, etc…
Raman maps can be merged with the topographical data to perform collage images.
|
|
|
Collage images of the diamond films surface with
Raman intensity
of the 1331 cm^-1 band (a) and 1525 cm^-1 band. |
Such collage images are presented in fig.8 by a 3D presentation of the data of a diamond film. The surface describes the topography variation and the colures indicate the intensity of the 1331 cm^-1 band (fig. 8a) and the 1525 cm^-1 band (fig. 8b). It is clearly seen that the combined data shows the materials composition within the topographic image and the direct location of each band. The green arrows show the Carbon (1525 cm^-1 band) locations on the surface when the 1525 cm^-1 band intensity is mapped.
|
