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Updated: Jun 17, 2025

Infrared Degenerate Four-wave Mixing with Upconversion Detection for Quantitative Gas Sensing

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Published on: March 22, 2019

Room temperature detection of the (H₂)₂ dimer.

H Fleurbaey¹, S Kassi¹, A Campargue¹

¹Univ. Grenoble Alpes, CNRS, LIPhy, Grenoble, France. Alain.Campargue@univ-grenoble-alpes.fr.

Physical Chemistry Chemical Physics : PCCP

|August 8, 2024

Summary

Researchers achieved the first room temperature detection of the hydrogen dimer (H₂)₂. This breakthrough in van der Waals complex spectroscopy provides new insights into this elusive species.

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Area of Science:

Physical Chemistry
Spectroscopy
Quantum Mechanics

Background:

The hydrogen dimer (H₂)₂ is a weakly bound van der Waals complex.
It serves as a prototype for *ab initio* studies.
Previous detection was limited to low temperatures (20 K).

Purpose of the Study:

To achieve the first room temperature detection of the hydrogen dimer (H₂)₂.
To analyze its partly resolved rotational structures.
To provide a benchmark for theoretical studies.

Main Methods:

Cavity ring down spectroscopy (CRDS).
Sub-atmospheric pressures.
Detection in the 1.2 μm region (H₂ first overtone band).

Main Results:

First room temperature detection of (H₂)₂.
Partly resolved rotational structures were observed.
Quantitative analysis of absorption features near monomer transitions.

Conclusions:

Demonstrated the feasibility of room temperature (H₂)₂ detection.
Provided insights into the structure of the hydrogen dimer.
Established a benchmark for future theoretical and experimental studies.