Optical and Vibrational Spectroscopy: FTIR, Raman Scattering, Tunable Diode Laser Absorption Spectroscopy (TDLAS), and Optical Gas Imaging (OGI) for Methane Leaks

Deep End Era. Engineering with Sankalp · Oct 29, 2026 · 1h 11m

Every chemical bond is a quantum spring oscillating at tens of trillions of hertz. We build optical and vibrational spectroscopy from first principles: IR dipole vs Raman polarizability selection rules, FTIR interferometry and the Fellgett, Jacquinot, and Connes advantages, TDLAS 2f/1f wavelength modulation, Cavity Ring-Down, and Optical Gas Imaging of fugitive methane leaks.

Chapters

00:00:00 Opening: The Invisible Plume Above the Compressor Deck

00:04:27 Molecular Vibrations as Quantum Springs: Wavenumbers, Anharmonicity, and 3N-6 Normal Modes

00:09:46 Infrared Absorption vs. Raman…