Related Experiment Video
Updated: May 14, 2026

Infrared Degenerate Four-wave Mixing with Upconversion Detection for Quantitative Gas Sensing
Published on: March 22, 2019
Absolute spectroscopy of N2O near 4.5 μm with a comb-calibrated, frequency-swept quantum cascade laser spectrometer
Kevin Knabe1, Paul A Williams, Fabrizio R Giorgetta
1National Institute of Standards and Technology, Boulder, Colorado 80305, USA.
Abstract:
We present absolute line center frequencies for 24 fundamental ν3 ro-vibrational P-branch transitions near 4.5 μm in N2O with an absolute expanded (multiplied by 2) frequency uncertainty of 800 kHz. The spectra are acquired with a swept laser spectrometer consisting of an external-cavity quantum cascade laser whose instantaneous frequency is continuously tracked against a near-infrared frequency comb. The measured absorbance profiles have a well-calibrated frequency axis, and are fitted to determine absolute line center values. We discuss the main sources of uncertainty.
Related Concept Videos
UV–Vis Spectroscopy: Molecular Electronic Transitions
Molecular Spectroscopy: Absorption and Emission
Atomic Absorption Spectroscopy: Instrumentation
The atomizer used in AAS can be either a flame atomizer or an...
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...
Atomic Emission Spectroscopy: Instrumentation
Atomic Absorption Spectroscopy: Lab
Solutions containing organic solvents, such as low-molecular-mass alcohols, esters, or ketones, enhance absorbances by increasing nebulizer...

