Related Experiment Video
Updated: Jul 5, 2026

Infrared Degenerate Four-wave Mixing with Upconversion Detection for Quantitative Gas Sensing
Published on: March 22, 2019
Mid-infrared spectroscopic investigation of methylamines by a continuous-wave difference-frequency-generation-based
Dilyan Marinov1, Julien Rey, Markus W Sigrist
1ETH Zürich, Institute for Quantum Electronics, Laser Spectroscopy and Sensing Laboratory, Schafmattstrasse 16, CH-8093 Zurich, Switzerland.
Abstract:
A laser spectroscopic system based on a cw difference-frequency generation source with a ratiometric multipass absorption detection scheme was employed for high-resolution spectroscopic investigation of gas-phase monomethylamine (MMA), dimethylamine (DMA), and trimethylamine (TMA). Possible application of the system as a noninvasive human breath analyzer for renal and liver diseases is targeted. The system operates in the fundamental C-H stretch absorption region around 2740-2860 cm(-1). A detection sensitivity of 2 x 10(-6) cm(-1) Hz(-(1/2)) (for signal-to-noise ratio SNR=1) is achieved, corresponding to detection limits of 900 ppb (parts in 10(9)) for MMA, 450 ppb for DMA, and 120 ppb for TMA in mixtures containing H2O and CO2 with concentrations of up to those present in human breath (2% and 5%, respectively). Future developments are discussed to further improve these detection limits that are currently still about 2 orders of magnitude higher than required for direct methylamine monitoring in human breath.
More Related Videos
Related Concept Videos
NMR Spectroscopy Of Amines
IR Frequency Region: Fingerprint Region
The...
IR Spectroscopy: Molecular Vibration Overview
Stretching vibrations are vibrational motions that occur along the bond line, changing the bond length or distance between two bonded atoms. They are further distinguished as symmetric or asymmetric. In symmetric stretching, the...
Mass Spectrometry of Amines
Chemical Shift: Internal References and Solvent Effects
The internal reference compound generally used in NMR spectroscopy is tetramethylsilane (TMS). TMS is preferred because it is chemically inert, soluble in NMR solvents, and easily removable. Also, the highly shielded methyl protons in TMS yield an intense...
¹³C NMR: Distortionless Enhancement by Polarization Transfer (DEPT)

