Usage Guide

This guide explains how to use MELT to search and visualize molecular emission lines.

Accessing MELT

Visit the live tool at https://copland-yz.github.io/MELT/

Works in any modern web browser (Chrome, Firefox, Safari, Edge). No installation required.

Basic Workflow

1. Filter by Elements

Click elements in the periodic table:

First click (green) - Include this element
Second click (red) - Exclude this element
Third click (gray) - Reset to neutral

Example: You know the system must include C, maybe O and H. You can Click C once (it should look green), then use the button to quickly exclude all elements at once. Then click O and H once, make them gray. The results will give C₂, CO, CH₂O, C₂H₄ etc.

2. Set Wavelength Range

Enter minimum and maximum values, then select your unit:

nm (nanometers) - Most common
Å (Ångström) - Traditional spectroscopy
μm (micrometers) - Infrared
GHz (gigahertz) - Radio/microwave
cm⁻¹ (wavenumber) - IR spectroscopy

Tip: Start with small ranges (<100 nm) for faster searches.

3. Search

Click the “Search” button. Results appear in the table below showing:

Molecule formula
Spectroscopic system
Wavelength (nm and Å)
Energy levels
Intensity (when available)
Source reference

4. Generate Spectrum

To create a synthetic spectrum:

Check boxes next to lines you want
Set the Peak Width (FWHM) to match your instrument resolution
Click “Generate Spectrum”
Use mouse to zoom/pan the plot

The FWHM (Full Width at Half Maximum) controls peak broadening:

High resolution: 0.01-0.1 nm
Medium resolution: 0.1-1 nm
Low resolution: 1-10 nm

5. Export Data

Download your results:

TXT - Tab-separated text
CSV - For Excel/Sheets
PNG - Spectrum image

Troubleshooting

No Results Found

Try wider wavelength range
Remove element filters (reset to gray)
Check units are correct

Too Many Results

Narrow wavelength range
Add element filters
Focus on specific molecules

Spectrum Not Generating

Make sure at least one line is selected
Check FWHM value is reasonable
Refresh page if needed

Tips

Small ranges (<100 nm) search faster
Element filters dramatically speed up searches
FWHM should match your spectrometer resolution
Save exports with descriptive filenames
Browser zoom (Ctrl +/-) adjusts interface size