About RDRS SpectraLib
A comprehensive, instrument-grade web application designed for the visualization, advanced processing, and high-speed mathematical matching of Raman and infrared spectra. Built to process proprietary laboratory data alongside massive open-source reference libraries.
Data Privacy Guarantee: All spectrum parsing and processing happens completely locally in your browser. Your raw data files and spectra are never uploaded, saved, or collected by RDRS SpectraLib server.
Scientific Use & Citations
RDRS SpectraLib is provided as a free tool for the academic and scientific community. If you use RDRS SpectraLib in your scientific work, publications, or presentations, please reference the software as:
Apopei A. I. 2026. RDRS SpectraLib - integrated spectral library & analysis web platform, version v26.4.18a, https://rdrs.uaic.ro
- Please ensure you insert the current version number (found in the top right header).
- You may leave out the part in quotation marks.
- (And please, try to get the spelling right!)
Developed by Andrei Ionuț Apopei, PhD
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Features marked with this badge require a verified researcher account due to server compute limits and database copyright protections.
Basic Workflow (Multiple Spectra)
RDRS SpectraLib is designed to handle dozens of spectra simultaneously. When you open any processing tool (like Smooth or Baseline), you will see a list of all your loaded spectra.
- Check the boxes next to the spectra you want to process. (Visible spectra in the chart are checked by default).
- Select your settings and click Apply.
- By default, RDRS SpectraLib keeps your original data and creates a brand new, processed copy with a tag (like
[SG] or [Cut]) added to the name.
Data Protection & Export Restrictions
RDRS SpectraLib operates under strict licensing agreements with external providers (such as RRUFF™ and ROD). To protect the intellectual property of these databases, certain restrictions are enforced:
- Export Block: Reference spectra loaded from the Database or generated via the Match tool cannot be exported as raw data files (CSV, TXT, or JCAMP-DX).
- Derived Protection: Any spectrum created by processing a reference file (e.g., Smoothing, Baseline Correction, or Averaging a reference) inherits this protection and remains locked.
- Project Saves: When saving a Project (.json), protected reference spectra are automatically stripped from the file to prevent unauthorized redistribution of raw database arrays.
Note: These restrictions apply ONLY to database references. Your own uploaded laboratory data remains fully exportable and accessible at all times. You can always include reference spectra in your Professional PDF Reports for publication and visual comparison.
Reference Database
Load pure, verified reference spectra directly into your chart for visual comparison.
How to use: Type a mineral name (e.g., "Quartz") into the Global Search, or use the dropdowns to browse by Technique and Class. Check the boxes of the minerals you want, and click Add to Chart. Hovering over a result will show a live preview overlay.
Data Sources & Citations
-
RRUFF Project: A comprehensive collection of 14,000+ Raman and infrared spectra of minerals, provided by the University of Arizona. When publishing data analyzed using these reference matches, please cite:
Lafuente, B., Downs, R. T., Yang, H., & Stone, N. (2015). The power of databases: the RRUFF project. Highlights in Mineralogical Crystallography, T Armbruster and R M Danisi, Eds., Berlin, Germany, W. De Gruyter, 1–30.
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Raman Open Database (ROD): An interconnected open-access resource for Raman spectroscopy and X-ray diffraction material identification. Please cite:
El Mendili, Y., Vaitkus, A., Merkys, A., Gražulis, S., Chateigner, D., Mathevet, F., ... & Le Guen, M. (2019). Raman Open Database: first interconnected Raman–X-ray diffraction open-access resource for material identification. Applied Crystallography, 52(3), 618-625.
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RDRS SpectraLib Database: Our proprietary internal database. Currently under active development (spectra organization and processing phase).
Buzgar N., Apopei A. I., & Buzatu A. (2009). Romanian Database of Raman Spectroscopy (https://rdrs.uaic.ro).
Match Spectrum to Database
Identify an unknown sample by comparing it against our 11,400+ reference library using traditional mathematical algorithms or advanced Artificial Intelligence.
Available Algorithms:
- Machine Learning: Features models trained specifically on pure Raman, Infrared (FT-IR), and X-Ray Diffraction (XRD) datasets. Achieves high validation accuracy by intelligently ignoring noise and background humps. Best for identifying the single dominant phase in a sample.
- AI: Multi-Phase Mixture (Experimental): A multi-label neural network designed to untangle and identify multiple overlapping minerals in a single mixed rock. (Available for standard Raman and XRD). Use the Sensitivity Slider to adjust detection limits: lower it to find hidden trace minerals, or raise it to prevent false positives.
- 1st Derivative: The traditional gold-standard. Mathematically strips away sloped baselines to match pure peak inflection points.
- Pearson / Cosine: General curve shape and intensity correlation matchers.
How to use:
- Select exactly one unknown spectrum from the list.
- Select the correct Database Category to route your data to the appropriate AI brain. (Ensure your X-axis units match the required format for that technique!)
- Select your algorithm. (If using the Multi-Phase Mixture, adjust your Sensitivity threshold).
- Click Find Best Matches.
Pro Tip for Mixtures: The Multi-Phase AI is highly sensitive to background fluorescence and amorphous humps. Always run an Auto Baseline (ALS) on your sample before matching to ensure maximum accuracy!
Note: Results are paginated. You can load up to the top 50 closest matches by clicking "Show Next 10 Results" at the bottom of the list.
Spectra Galaxy
Visualize the entire reference database as an interactive 2D map using UMAP (Uniform Manifold Approximation and Projection). Minerals with similar molecular structures and spectral fingerprints naturally cluster together into physical "galaxies".
Available Analytics & Color Maps:
- Chemical Superclass (Dana): Categorizes minerals into standard families (Silicates, Carbonates, Sulfates, Oxides, etc.) based on their elemental composition.
- Primary Peak Position: Applies a continuous thermal heatmap based on the location of the absolute highest intensity peak in the spectrum.
- Spectral Entropy: Maps the mathematical "messiness" or complexity of the signal. Clean, sharp spectra contrast heavily against highly fluorescent data or complex mixtures.
- Center of Mass: Maps the weighted centroid of the spectral curve, highlighting regions where the bulk of the scattering or diffraction occurs.
How to use:
- Select one unknown spectrum from your workspace to automatically project it onto the map as a Yellow Star (⭐). (Or select none to freely browse the database).
- Select the correct Instrument Category (Raman, FT-IR, or XRD) from the Galaxy Controls to load the corresponding universe.
- Use the Color Map By dropdown to analyze the clusters, and drag/scroll to pan and zoom around the map.
- Click any dot in the cloud to instantly compare its database reference against your target in the bottom-right 1D Spectrum Comparison panel.
Pro Tip for Visual Matching: In the 1D Comparison panel, both your target spectrum and the database reference are auto-normalized from 0 to 1. This allows you to perfectly compare peak alignments and curve shapes, even if the absolute raw intensities are drastically different!
Note: The points physically closest to your Target Star on the 2D map are mathematically your most likely phase matches. If you lose your place while panning, click "Locate My Target Spectrum" to snap the camera back.
Plot Digitizer
A massive quantity of historical and technical data is only available as chart images in published PDFs. The Plot Digitizer uses a combination of computer vision techniques and manual inputs to recover raw data arrays from these images.
Phase 1: Axes Calibration
Before extracting data, you must map the image pixels to real data values. You must specify four points: X1, X2 on the X-axis, and Y1, Y2 on the Y-axis.
- Click Set X1, then click a tick mark on the left side of the chart's X-axis. Type the known data value into the box.
- Repeat this for X2 (right side of X-axis), Y1 (bottom of Y-axis), and Y2 (top of Y-axis).
- Pro-Tip: For best accuracy during the digitization process, pick points that are as far away from each other as possible.
Phase 2: Data Extraction
- Manual Mode: Click Add Points Mode and manually click along the curve to extract data points. Use the Undo or Clear buttons to adjust your output.
- Auto (AI) Mode: Uses computer vision to automatically trace colored lines.
- 1. Mask: Use the highlighter to paint over the specific curve you want. This limits the AI's search to your specified region, ignoring intersecting lines and text.
- 2. Color Target: Click the eye-dropper and select the exact color of the curve from the image.
- 3. Run: Click Run Auto-Extraction. The AI will place points along the center of the line.
Phase 3: Generate Spectrum
Once you are satisfied with the extracted points, click the green Generate Spectrum button in the top right. RDRS SpectraLib will automatically convert your pixels into physical units using your calibration data and push the new spectrum directly into your main workspace for analysis!
Advanced Plot Configuration
RDRS SpectraLib gives you deep, publication-level control over how your data is rendered on the screen. These settings are cached in your browser so your preferred lab aesthetic loads automatically every time.
- Global - Rendering Engine: SVG is the default engine (crisp lines, perfect for PDF exports). WebGL offloads rendering to your GPU for 60fps panning when analyzing massive datasets (50+ spectra), though filled areas may show minor artifacts.
- Global - Mirror Axes: Draws a solid bounding box around the top and right sides of the chart, replicating your tick styles. This is the standard aesthetic for most scientific journals.
- Axis Scales (Linear vs Logarithmic): Logarithmic scales are incredibly useful when a massive fluorescence hump dwarfs a tiny Raman signal. Note: Log scales require strictly positive data.
- Ticks & Grids: Independently toggle gridlines, axis lines, and minor ticks for the X and Y axes. You can also change the direction of major ticks (Inside, Outside, Cross, or Hidden) to match specific publication formatting rules.
Pro-Tip: If you ever accidentally hide your axes or mess up your chart layout, click File > Reset Settings at the top of the screen to instantly restore the default factory view!
Workspace & Sidebar Management
Manage large datasets efficiently using the built-in file explorer tools.
- Folders: Click the New button at the bottom of the sidebar to create virtual folders. Grouping spectra allows you to instantly toggle visibility () or delete an entire dataset with a single click.
- ☰ Drag & Drop: Reordering is permanently unlocked! Click and drag the handle next to any spectrum to arrange your list, or drop it onto a folder header to organize it. The chart's layering updates dynamically to match your list.
- Live Filter: When 2 or more spectra are loaded, a search bar appears at the top of the sidebar. Type any part of a name to instantly filter your list. Folders containing matching spectra will automatically expand to show you the results.
- Renaming: Click the pen icon next to any spectrum or folder to rename it inline. Press Enter to save.
- Batch Rename: Click the signature icon on any folder header to rename all spectra inside it simultaneously. Use dynamic variables like
<Name> and <Inc 0Nr> to instantly generate organized naming patterns for your clusters.
Display Settings
Visual toggles to customize your workspace appearance. These do not mathematically alter raw data arrays.
- Flip X: Reverses the X-axis direction.
- Legend: Cycles the chart legend between Outside, Floating, and Hidden.
- Grid: Toggles background layout gridlines.
- Reset View: Instantly restores default zoom, offsets, tools, and display states.
- Lines: Cycles the rendering engine between continuous Lines, independent Points, or Both. Use Width to adjust thickness.
- Labels: Adjusts the font size of detected peak annotations.
- Fill: Shades the area under the curve. Reveals a dynamic UV-Vis rainbow gradient if your X-axis is set to [nm].
Interactive Tools
Tools that modify the chart's physical layout and active tracking.
- Stack: Vertically separates overlapping spectra by a standard offset (Δ).
- Auto-Norm: Temporarily min-max scales all spectra to a 0-1 range for visual comparison without changing the underlying raw detector counts.
- Drag Y: Activate this to physically click and drag spectra vertically across the chart for rapid visual alignment.
- Cursor: Click anywhere on the chart to drop vertical tracking lines. Useful for identifying peak boundaries before integration.
- Ridgeline: Creates a pseudo-3D overlapping "mountain" effect. Spectra are automatically normalized to [0,1] and filled to their baseline. Perfect for visualizing peak shifts across massive datasets. Adjust the Δ (Stack Offset) input to control the exact amount of overlap!
- Heatmap: Instantly transforms all visible spectra into a dense 2D color contour plot. Perfect for visualizing temperature series or spatial mapping.
- Freehand Edit: Danger! Manually "paint" over massive artifacts to force the data down to zero. Note: This permanently alters the raw data points.
- Manual Baseline: Click to physically drop and draw a custom baseline under your peaks. Turn on the Snap magnet to lock your clicks directly to the true data line.
Cut Range & Scale Y
- Cut Range: Deletes all data outside of the X-bounds you provide. Excellent for removing noisy detector edges.
- Scale: Multiplies the intensity by a specific factor. Note: You can also visually scale spectra without altering the raw data by changing the
×Scale box in the left sidebar next to the spectrum name!
Data Interpolation (Resampling)
Increases or decreases the data density of your spectrum and forces it onto a strict, uniform X-axis grid. Note: Interpolation does not increase the true optical resolution of your spectrometer; it is primarily used to align disparate datasets so they can be processed by matrix-based chemometrics (like PCA or 2D-COS).
Available Algorithms:
- Akima Spline: The gold standard for spectroscopy. A specialized monotone spline that resists overshooting. It perfectly smooths data while strictly preserving the local shape, preventing fake negative dips around sharp Raman peaks.
- Natural Cubic Spline: Creates an extremely smooth polynomial curve. Warning: Susceptible to "Runge's Phenomenon" (Ringing). If you have a sharp peak next to a flat baseline, a cubic spline will mathematically overshoot and create an artificial negative crater at the base of the peak.
- Linear: Simply draws straight lines between existing points. Mathematically safe with zero artifacts, but leaves low-density peaks looking like jagged triangles.
How to use: Enter a new Step Size (e.g., 1.0 for a point every 1 cm⁻¹). Leave the X Start and X End bounds blank to automatically use the spectrum's current limits.
Zap Peak (Excise)
Removes bad data points (like stubborn artifacts or saturated solvent peaks) and heals the gap with a clean, interpolated line.
How to use: Input the exact X-axis center of the bad peak, and how wide the cut should be. RDRS SpectraLib will delete the data in that window and draw a straight line connecting the two broken ends.
Cosmic Ray Removal (Despiking)
Automatically detects and removes artificially sharp spikes caused by high-energy particles hitting the camera sensor.
- Derivative (Gradient) algorithm: The industry standard. Identifies cosmic rays by hunting for near-vertical instantaneous slopes (which true Raman peaks do not have). Excellent for preserving sharp diamond or silicon peaks.
- Z-Score (Median) algorithm: Best for broader artifacts or saturated pixels.
Tip: Keep Live Preview checked! The red dashed line will show you exactly what the cleaned spectrum looks like before you apply it.
Spectral Alignment (Cross-Correlation)
Fixes instrument drift. Minor temperature changes in a laboratory can cause a spectrometer's laser to drift, shifting the X-axis slightly over time. If you run PCA or LCF on shifted peaks, the math will model the instrument drift instead of the actual chemical variance.
The Math: RDRS SpectraLib uses a 1st Derivative Global Cross-Correlation algorithm. Instead of dynamically stretching or warping the X-axis (which destroys quantitative peak areas), this algorithm slides the entire spectrum left and right to find the perfect overlap with your anchor reference. This strictly preserves your physical peak shapes, FWHM, and Integration Areas.
Pro-Tip: The Max Shift Parameter.
If you try to align two completely different minerals, the algorithm might jump wildly to force two unrelated peaks to overlap. The Maximum Allowed Shift (default 50 points) restricts the math from searching too far. For standard thermal laser drift, a shift limit of 20 to 50 points is usually perfect.
Smoothing
Reduces high-frequency detector noise. Selecting the right algorithm and window size is critical to reducing noise without artificially broadening your actual chemical peaks.
Available Algorithms:
- Savitzky-Golay: The gold standard for vibrational spectroscopy. It fits a local polynomial across the sliding window. (Preserves sharp peak heights and widths much better than standard averaging. Lower polynomial order = smoother curve).
- Moving Average: A traditional sliding filter. Rectangular weights all points in the window equally, while Triangular gives more weight to the center point (better for preserving peak tips).
- Percentile Filter: A non-linear ranking filter. Setting it to <50% creates a standard Median filter. Setting it lower (<50%) is excellent for mathematically flattening out sharp cosmic rays or artificial spikes that ride on top of the true baseline.
Region-Specific Smoothing: Don't blur pristine peaks just to fix a noisy detector tail! Enter an X Start and X End to apply the smoothing filter only to a specific noisy section of your spectrum. Leave the inputs completely blank to smooth the entire array.
Normalization & Preprocessing
Mathematical scaling and scattering corrections to prepare your data for advanced chemometrics.
- 0 → 1 / 0 → 100% (Min-Max): Scales the Y-axis so the lowest point is 0 and the highest is 1 (or 100). Essential before running Hierarchical Cluster Analysis (HCA) so weak and strong acquisitions of the same mineral group together properly.
- Divide by Max: Scales the highest peak to 1, but leaves the baseline wherever it naturally falls.
- SNV & MSC (Scatter Correction): Standard Normal Variate and Multiplicative Scatter Correction eliminate physical baseline shifts and multiplicative scattering effects caused by sample surface roughness (e.g., in powders). Highly recommended before PCA Clustering.
- Mean-Centering: Subtracts the average of the dataset from every spectrum. Mandatory prerequisite before running Train & Predict (PLS-R/SVM) models.
Automatic Baseline Correction
Removes thermal noise, fluorescence, or sloped backgrounds from your data.
- Auto Baseline: Uses advanced algorithms to mathematically guess the background. ALS (Asymmetric) is the gold standard for massive fluorescent humps. Adaptive (SNIP) is also excellent for Raman, while Scattering (Poly) handles broad, wavy backgrounds.
Shift X-Axis
Corrects instrumental calibration errors by manually shifting the data horizontally.
How to use: Enter a positive number to shift the peaks to the right (higher wavenumbers), or a negative number to shift them to the left. The Y-intensities remain completely unchanged.
Unit & Axis Conversions
A unified tool to mathematically transform your data arrays or fix imported metadata.
- Vibrational Math: Converts physical X units for optical spectroscopy (e.g., nm ↔ cm⁻¹, eV, THz). Note: Formulas like nm to eV mathematically reverse the array, which RDRS SpectraLib handles and re-sorts automatically.
- Diffraction Math (XRD): Uses Bragg's Law (nλ = 2d sinθ) to convert between 2-Theta angles and physical d-spacing.
- XRD Target Conversion: Crucial for AI Matching! The RDRS AI models are trained exclusively on Copper (Cu Kα1) radiation. If your diffractometer used a different anode (like Cobalt or Molybdenum), you must use this tool to mathematically convert your 2-Theta angles to the Copper standard before running a match.
- Y-Axis Math: Converts intensity scales (e.g., Transmittance % ↔ Absorbance).
- Rename Labels: Overwrites the global axis titles for your PDF reports without altering the underlying raw data points.
Batch Processing Pipeline (Macros)
The ultimate power-user tool. Apply an entire sequence of mathematical operations to dozens of spectra with a single click.
How to use: Check the boxes for the operations you want to apply (Cut, Smooth, Baseline, Normalize), adjust the specific parameters, and click Run Pipeline. RDRS SpectraLib will sequentially chain the math together in the background.
Find Peaks
Automatically detect and label peaks (maxima) or valleys (minima) based on height thresholds.
When peaks are found, RDRS SpectraLib automatically calculates the FWHM (Full Width at Half Maximum) for crystallographic analysis. The results are automatically logged to the Console and exported in your PDF reports.
Integrate Peak Area
Calculates the area under a curve, which is proportional to chemical concentration.
How to use: Click the ✛ Cursor tool in the left panel to find the X-axis start and end points of your peak. Enter those numbers here. The Console Log will open and display the Total Area (down to zero) and the Net Area (above the local background).
Colorimetric Analysis (CIE 1931)
Extracts the true mathematical color (Hex code and x,y coordinates) from an emission or photoluminescence spectrum.
How to use: Your X-axis must be set to Wavelength [nm]. Input the X bounds to isolate the material's emission peak (carefully excluding the excitation laser/LED). The application integrates the area using standard CIE 1931 Color Matching Functions and outputs the precise color swatch directly to the Console.
Peak Curve Fitting (Deconvolution)
Resolves heavily overlapping peak clusters into individual mathematical components using Levenberg-Marquardt optimization. You can now model true physical and instrumental states by selecting specific Profile Shapes.
How to use:
- (Highly Recommended) Click Visually Pick Centers. The modal will become transparent. Click directly on the chart to drop vertical markers where you suspect hidden peak shoulders are located. (Right-click to undo, or use the trash icon to start over).
- Auto-Bounding: As you drop centers, RDRS SpectraLib will automatically calculate the optimal X Start and X End bounds to isolate the cluster for you! (You can still type these manually if needed).
- Click Finish Picking.
- Select your Profile Shape. (See the guide below).
- If you choose to skip visual picking, manually enter your X-bounds and select the Number of Peaks (up to 10) to force the solver to blindly guess.
- Click Run Optimization.
Which Profile Shape should I choose?
- Gaussian: Best for modeling the blur caused strictly by the instrument/spectrometer (slits, gratings).
- Lorentzian: Best for modeling the true physical nature of the sample, such as vibrational lifetime decay (Raman) or crystallite size/strain (XRD).
- Pseudo-Voigt (Mixed): The absolute gold standard for real-world data. It perfectly blends Gaussian (instrument) and Lorentzian (sample) profiles together.
Why pick centers visually? Blindly guessing peak locations often causes the math to fail on asymmetric data. By clicking the exact X-coordinates, you give the algorithm a perfect starting line, guaranteeing sub-second convergence for complex overlaps.
Advanced Solver Parameters: If your data is extremely noisy and triggers an 'Optimization failed to converge' error, expand the Advanced Parameters drawer. Increase the Max Iterations (e.g., 20000) or lower the Tolerance (e.g., 1e-6) to force the math to solve it.
Derivative Spectroscopy
Calculates the 1st or 2nd derivative to identify hidden shoulders or overlapping bands. Because derivatives amplify signal noise exponentially, always apply a Savitzky-Golay Smooth prior to using this tool.
Spectral Stripping (Subtract)
Used to mathematically remove a pure reference phase from a mixed sample spectrum.
How to use: Select your mixed sample (Minuend) and the pure database reference (Subtrahend). Slowly drag the multiplier slider. Watch the chart update live until the reference peaks visually disappear from your mixed sample.
Merge Spectra (Stitch)
Combines multiple spectral segments (e.g., from a dual-grating spectrometer) into one continuous trace.
How to use: Select the spectra you want to weave together. RDRS SpectraLib will automatically sort them by X-axis, interpolate any empty gaps, and average any overlapping regions to create a single, seamless line.
Add & Divide Spectra
Perform direct mathematical operations between multiple target spectra and a single reference spectrum.
- + Add Spectra: Adds the Y-values of a reference spectrum to your selected targets.
- ÷ Divide Spectra: Divides your target spectra by a reference spectrum. Essential for calculating Transmission/Reflectance ratios.
Auto-Alignment Magic: RDRS SpectraLib will automatically interpolate the reference data to perfectly align with each target's X-axis before calculating the results.
Spectrum Averaging & Variance
Calculates the Mean (average) of multiple spectra. Highly recommended for heterogeneous samples where multiple acquisitions were taken. If you check Draw ±1 Std. Dev., it will draw a semi-transparent shaded area behind the main line representing the sample variance!
Exploratory Cluster Analysis
Advanced unsupervised Machine Learning techniques that reduce the dimensionality of complex spectra, compressing thousands of data points into a 2D scatter plot to group chemically similar spectra together.
Available Algorithms:
- PCA (Linear): Best for understanding global variance and identifying the exact physical peaks that drive the separation between samples.
- t-SNE (Non-Linear): Highly effective at untangling complex, overlapping data into tight, distinct local clusters.
- UMAP (Hybrid): The modern successor to t-SNE. Creates distinct local clusters while mathematically preserving the global distances between groups.
How to use: Select at least 3 spectra, choose your algorithm, and click Compute. Depending on your choice, the dashboard will display:
- Scree Plot (PCA Only): Shows how much physical variance is explained by each Principal Component (PC). The curve flattens out when the remaining components are just noise.
- Loadings (PCA Only): Shows the physical Raman shifts (or wavelengths) that are driving the separation in the clusters. Peaks here indicate why spectra are grouping together.
- Scores Matrix (All Algos): The main scatter plots. Chemically identical spectra will cluster together. The diagonal plots (KDE) show the statistical distribution (bell curves) of your data. (Expands to full screen for t-SNE and UMAP).
Pro-Tip 1: Group by Folders! If you organize your spectra into Folders in the left sidebar before running your analysis, the matrix will pull their exact colors and automatically calculate/draw 95% Confidence Ellipses around your groups!
Pro-Tip 2: Interactive Filtering. Spot a weird outlier? Click any dot on the Matrix to instantly hide/show that specific spectrum. Or, use the Lasso tool to circle a whole cluster of outliers and click Hide Selected in the top right. When you click "Exit Dashboard", your main workspace will reflect your choices!
Hierarchical Cluster Analysis (HCA)
HCA is an advanced unsupervised chemometric technique that calculates the mathematical distance (variance) between spectra and groups them into a "family tree" called a Dendrogram. It is the gold standard for classifying unknown samples or proving that different acquisitions belong to the exact same mineral phase.
How to use:
- Select at least 3 spectra (the more, the better).
- (Optional) Check Include Distance Matrix Heatmap if you want to visualize the exact Euclidean distance between every single pair of spectra as a 2D color grid.
- Click Build Tree.
How to read the results:
- Dendrogram (Tree): Spectra connected by short branches are mathematically nearly identical. The longer the horizontal branch stretches before it merges with another, the more chemically distinct those groups are.
- Heatmap (Matrix): Dark purple/blue squares mean the two intersecting spectra have zero variance (identical). Bright yellow squares indicate completely different materials.
Pro-Tip: The HCA algorithm compares absolute Y-intensities. To prevent a strong spectrum and a weak spectrum of the same mineral from being clustered into separate groups, you should always mathematically Normalize (0 → 1) your dataset before running HCA!
Train & Predict (Chemometrics)
Build custom Machine Learning models (PLS-R or SVM) directly in your browser to predict continuous concentrations or classify unknown samples.
- PLS Regression (PLS-R): Predicts continuous numbers (e.g., % Concentration, Temperature, Hardness). Requires strictly numerical training values.
- SVM Classification: Predicts categorical groups (e.g., "Cancer" vs "Healthy", or "Quartz" vs "Calcite").
The Proper Workflow:
- Pre-process: Your data must be mathematically clean to prevent the algorithm from memorizing background noise. Apply Auto Baseline → Cut Range (to isolate the active peaks) → SNV → Mean-Centering.
- Assign Training Data: Open the Train & Predict tool. Type your known values (e.g., "85") into the boxes next to your reference spectra.
- Assign Unknowns: Leave the boxes completely blank for the spectra you want the AI to predict.
- Click Train Model & Predict. The results will be automatically logged to the Console for easy copying to Excel.
Understanding the Diagnostics Pill:
Before spitting out predictions, the server runs a strict Leave-One-Out Cross-Validation (LOOCV). If the resulting R² Score is green (> 0.90), your model is highly trustworthy. If it flashes red, your data requires better pre-processing (or you need to adjust the PLS Components parameter to prevent underfitting or overfitting the noise).
Peak Trend Analysis (SPLOM)
Generates a Scatterplot Matrix (SPLOM) to track how a specific peak's Position (X), Intensity (Y), FWHM, and Area evolve across a sequence of files. Essential for kinetics, thermal degradation, and phase transition studies.
How to use:
- Run the Find Peaks tool on your loaded dataset to extract the mathematical parameters.
- Open the Trend / SPLOM tool.
- Click Visually Pick Target Peak and click the specific peak you want to track on the main chart.
- Click Generate Correlogram. The algorithm will hunt for that peak in every file (within your specified ± Tolerance window) and map the correlations.
Pro-Tip 1: Deep Zoom. Click and drag a box inside any subplot to instantly zoom into specific clusters across all dimensions simultaneously. Double-click the chart to reset the view!
Pro-Tip 2: Interactive Filtering. The dots in the SPLOM inherit the exact colors of your spectra. Click any individual point to instantly hide or show that specific spectrum in your main workspace!
2D Correlation Spectroscopy (2T2D)
Two-Trace Two-Dimensional (2T2D) Correlation Spectroscopy mathematically analyzes how spectral bands change across a dynamic dataset. It spreads highly overlapping 1D peaks across a 2D plane to resolve hidden components and track physical changes.
1. What spectra should I load?
- The Rule of Variance: 2D-COS analyzes changes. You need at least 2 spectra, but loading a series of 5 to 30 spectra (e.g., a temperature ramp, a time-series/kinetics run, or a solid-solution compositional shift) yields the best results.
- The "Average" Reference: The algorithm automatically calculates the mean of your selected spectra to use as the baseline reference point. Spectra that deviate from this average will generate the 2D cross-peaks.
- Crucial Prep: You must apply Auto-Baseline correction before running 2D-COS. Because the math is highly sensitive to variance, sloped or floating fluorescent baselines will drown out the actual peak correlations!
2. How to read the Contour Maps:
- Synchronous Map (In-Phase): Highlights simultaneous changes.
- Auto-peaks (The Diagonal): The dense spots running bottom-left to top-right. These show the regions experiencing the greatest intensity changes across your dataset.
- Cross-peaks (Off-Diagonal): If Red (Positive), the two intersecting peaks are growing or shrinking together. If Blue (Negative), one peak grows while the other shrinks.
- Asynchronous Map (Out-of-Phase): The ultimate tool for resolving hidden phases.
- The Diagonal: Always mathematically zero (white/flat).
- Cross-peaks ("Butterflies"): Red and Blue off-diagonal clusters prove that the peaks are changing independently of each other. This is definitive proof of a peak shifting (due to chemical substitution/stress) or the presence of a completely different, hidden mineral phase.
3. The interactive slicer (numerical purification)
The Slicer isn't just a visualization tool; it acts as a numerical curve-resolution tool. By mathematical definition, a horizontal slice of an asynchronous 2T2D map taken at a specific characteristic peak is entirely devoid of the spectral contribution from that peak's species.
Workflow: Ensure Show 1D Margins is checked. Hover over the center of an Asynchronous "butterfly" cross-peak. Click it. The 1D slice on the right has now mathematically stripped away the interference from the peak pointing to the Y-axis. Click Save Extracted Slice to push this purified trace back into your workspace for further analysis!
Linear Combination Fitting (LCF)
Quantifies the percentage composition of a mixed sample using Non-Negative Least Squares (NNLS).
How to use: Baseline correct your mixed sample. Load the pure reference spectra from the database. Open the LCF tool, select the mixture as the Target, check the references, and calculate. The algorithm builds a synthetic "Fit" curve and logs the exact mathematical percentages to the Console.
MCR Blind Unmixing
Multivariate Curve Resolution (MCR-ALS) mathematically extracts the pure "hidden" components from a mixed dataset without needing a reference database.
How to use:
- Select your mixed spectra (e.g., a time-series of a chemical reaction or a spatial map).
- Input the number of pure components you suspect are in the mixture.
- Click Run Extraction. The algorithm will mathematically deduce the pure spectral signatures and add them directly to your chart.
MCR vs LCF: Use LCF Unmixing when you already know what minerals are in the rock and want exact percentages. Use MCR Blind Unmixing when you have absolutely no idea what is in the sample and need the math to blindly separate the phases for you.
Evaluate Quality (SNR)
Automatically calculates the Signal-to-Noise Ratio (SNR) for all visible spectra to help you quickly identify pristine data and flag noisy, unusable acquisitions.
How to use:
- Leave only the spectra you want to evaluate visible on the chart.
- Click the tool to open the configuration modal.
- Set your custom thresholds for what your specific lab considers Good vs Poor quality.
- Click Evaluate SNR.
Results will appear as colored badges directly in the left sidebar next to each spectrum's name.
UV-VIS Acquisition (Live Hardware)
Connect USB spectrometers, CMOS sensors, or Virtual Cameras (via OBS/SharpCap) directly to the browser for real-time photon digitization.
Hardware Note: For high-fidelity results, ensure you are using a global shutter sensor and have disabled "Auto-Exposure" and "Auto-White Balance" in the Camera Settings panel.
- Region of Interest (ROI): Use Extract Y and Slit Height to isolate the diffraction streak. Adjust Start/End X to crop dead sensor pixels; this significantly reduces CPU overhead on 4K sensors.
- Live Smooth (IIR): An Infinite Impulse Response temporal filter. Higher values integrate light over more frames, effectively suppressing high-frequency sensor noise (Dark Current) at the cost of responsiveness.
- Dark Frame Subtraction (D): Turn off your light source and click Set Dark to capture the sensor's thermal noise floor. Toggle Apply Dark to mathematically subtract this from every frame.
- Flat-Field Correction (W): Capture a "White" reference (e.g., a halogen lamp). Enabling Apply Flat calculates (Sample - Dark) / (White - Dark), correcting for non-uniform sensor sensitivity and vignetting.
- Kinetics Series: Automated time-lapse acquisition. Define an Interval and Total Captures to monitor chemical reactions. Results can be automatically piped into a 2-Theta Heatmap or 3D Waterfall view upon completion.
Wavelength Calibration [nm]
To convert raw pixels into physical units, use a known emission source (like a fluorescent lamp or laser pointer):
- Drop a Cursor on a known peak (e.g., Mercury 546.1 nm).
- Click Set P1 in the calibration panel. Repeat for P2 (and P3 for non-linear gratings).
- Click Apply Math. The system will calculate a Regression Fit (Linear or Quadratic) and project a dynamic UV-Vis rainbow beneath your data.
Use File > Save Calibration to export your regression coefficients. Authenticated users can auto-load these profiles in future sessions.