igor-swnt-massanalysis

A tool for performing statistical actions on top of a collection of spectra

measurement setup

The camera images and spectra from this program are loaded with PLEMd2 and recorded with a versatile labview program called PLEMv3

main functionality

The entry point is SMAload() and SMAadd() to define the spectra or images from a directory that should get loaded. Currently only ibw files are processed using PLEM.

The files are read from the file system using SMAread(). If the data files are at a specific location in the file system that differs from one machine to another, you can set the base path using SMASetBasePath which allows to reference all loaded objects relative to this path.

images

The sample used in this experiment consists of 2µm broad trench structure with Carbon Nanotubes freely suspended in air over trenches that are engraved on the substrate. The images are used to obtain the carbon nanotube positions. Carbon nanotubes from those positions are then used for spectra acquisition.

24 Images are combined to a single image that gives a good overview of the scanning range that is limited by the nanostage's lateral x and y positioning range.

The same procedure can be used for different cameras. Here we use a InGaAs Camera that records more carbon nanotubes but due to its larger pixel size is not as accurate as the silicon camera above:

From those images, good carbon nanotube positions are picked and a coordinate list is generated. From each position spectra are recorded:

You can manually add images using AddCoordinates or CTRL+1. The zero-position of the image is reset to the value on cursor A using SMAtasksZeroToCursor. You can delete points directly in the graph by marking them with a Marquee and right-clicking into the area and select Erase Points.

You can generate a scan of 11 points around each coordinate using SMAtasksGenerateExactscan. This is measurement type is referred to a "exactscan"

spectra

Simple spectra analysis can be done using

• SMAgetBestSpectra()
• SMAgetMaximum()

All spectra can be added to a single file using SMAgetSourceWave. The function is aware of mixed x-ranges and can use downsample to reduce calculation times. You can use CTRL+1 also in the "source graph" to select spectra using cursor A. Use SMAtasksGenerateCoordinates to extract the coordinates for the marked spectra.

A symmetric covariance can be calculated from the "source wave" using SMAcovariance. Wigner Transformation is generated using SMAWigner.

Mass peak analysis can be performed in a specified x range using SMAsinglePeakAction(hcsr(A), hcsr(B)) which is the method of choice if the peak position is the same for all spectra.

Otherwise use SMAquickAnalysis or SMApeakAnalysis. If you want to analyse a measurement of the "exactscan" type, use SMApeakAnalysisExactscan() which finds the best spectrum in a series of 11 spectra around a central location.