JASCO | Variable Analysis
→ Spectra Manager™ includes a wide range of additional software applications; some examples of more commonly used applications are shown here. For details of additional applications, please contact us.
Carbon Analysis
The physical properties of carbon are closely related to its structure. Raman spectroscopy is a powerful technique for the evaluation of carbon based materials.
Compared with the X-ray diffraction, dispersive Raman is not only sensitive to structural changes but also allows for the evaluation of amorphous materials, such as crystals. Normally, a Raman spectrum of a carbon material will have peaks at Raman shifts of 1580 cm-1 and 1360 cm-1. The ratio of the intensity of these two peaks (R=I1360/I1580) is used as an index indicative of the degree of crystallization.
The Carbon Analysis Program is used to estimate the carbon structure after the spectrum has been pretreated with the Curve Fitting Program.
Interval Measurement & Analysis
The interval scanning program is used to acquire spectral data during a time course measurement. This program is commonly used for long-term observation of spectral changes during reactions.
Both full spectrum and changes in intensity changes at a specified wavenumber can also be monitored. The spectral data can be displayed in 2D or 3D plot. Time course data based on peak height, peak area or peak shift at a specified wavenumber can be calculated.
A variant of this application, Temperature Control Interval Measurement can be used to measure Raman spectra in time intervals as a function of temperature together with Linkam Heating/Cooling Stages. This program is typically used for kinetic measurements of samples such as chemical reactions, polymer curing, and acceleration testing with increased temperature.
Two-Dimensional Correlation Analysis
The 2D correlation analysis program performs a time domain Fourier transform of time-resolved spectra, for example from interval scan measurements, then plots of the correlation intensities of the real (synchronous correction) and imaginary (asynchronous correction) portions are generated as contour heat maps.
Analyzing the correlation spectra of each plot provides an estimation of the chemical and/or structural changes in a sample. By combining these results with other types of spectral analysis, including Near-IR, Raman, UV-visible or Circular Dichroism, 2D correlation can provide an analysis of peak assignments, lattice vibrations or the relationship between intramolecular vibrations, color or chiral information.
Stress Analysis
This program calculates the amount of stress in a sample based on the difference between the peak wavenumber of a reference and of the sample. When lattice spacing between atoms changes due to internal stress, the peak position changes. If a force is applied to a substance producing strain in the crystal, the distance between the lattice changes. This phenomenon is observed in a Raman spectrum with a shift of the Raman peak.
For example, using a silicon crystal, a peak shift of 1 cm-1 corresponds to an applied pressure of 2.49 x 102 MPa. When measuring the stress of silicon using the 532 nm laser, a slight change in peak position can be accurately detected by measuring the emission line of Neon (wavelength of 540.056nm; absolute wavenumber at 18516.6 cm-1) that appears at 277 cm-1 simultaneously with the measurement of the sample’s Raman spectrum.
Reference data for calculating the stress value of an evaluation sample can be selected from arbitrary coordinate data in the same file or data collected using the mapping function.
Chemometrics Packages
Multivariate analysis is widely used for multicomponent mixtures. Various types of multivariate analysis algorithms are available such as CLS, PCR and PLS.
These are typically recommended for the quantitation of analytes in complex matrices, while PCA and MCR are suitable for classification of multicomponent samples. The chemometric techniques can be applied to single point spectra, mapping data files, as well as time interval measurement data.
Polysilicon Crystallinity Evaluation
The Polysilicon Crystallinity Evaluation program calculates the Volume fraction, Vf, for a Raman spectrum based on after the spectrum has been pretreated with the Curve Fitting application.
The calculation can be applied to single spectra, mapping data and interval measurement (time series) data.
