Chinese Scientists Develop Breakthrough DPA-SRS Laser Technique for Ultra-Sensitive Hydrogen Safety Monitoring

Researchers at the Chinese Academy of Sciences develop DPA-SRS, a new laser method to detect trace hydrogen at 1 ppm for enhanced industrial safety.

By: AXL Media

Published: Mar 26, 2026, 4:52 AM EDT

Source: Information for this report was sourced from the Hefei Institutes of Physical Science, Chinese Academy of Sciences.

The Challenge of Monitoring Infrared-Inactive Gases

Hydrogen is widely recognized as a cornerstone of the future clean energy economy, yet its physical properties make it notoriously difficult to monitor for safety. Unlike many other gases, hydrogen lacks a permanent dipole moment, rendering it "infrared-inactive" and invisible to conventional absorption-based sensors. While Raman spectroscopy has long been used for molecular fingerprinting, the resulting signals are often too weak for high-sensitivity applications. This technological gap has historically hindered the deployment of reliable, real-time hydrogen sensors in high-risk industrial settings where rapid leak detection is a critical safety requirement.

Engineering the DPA-SRS Excitation Field

To address these sensitivities, the team from the Hefei Institutes of Physical Science integrated stimulated Raman scattering with photoacoustic detection. The process utilizes a 532 nm pump beam to generate a high-intensity 683 nm Stokes beam, creating a dual-color excitation field. When this field matches the specific vibrational energy levels of hydrogen molecules, it induces stimulated Raman transitions. These transitions are followed by a vibration-to-translation (V–T) relaxation process, effectively converting molecular excitation into a physical acoustic signal that can be measured with extreme precision.

Advanced Acoustic Signal Processing

The core of the hardware innovation lies in a custom-designed differential H-type resonant photoacoustic cell. This specialized chamber is paired with advanced weak-signal processing algorithms to filter out environmental noise and amplify the subtle acoustic signatures of trace hydrogen. By refining the interaction between the laser beams and the gas molecules, the proposed DPA-SRS system achieved a minimum detection limit of 0.65 ppm. This level of sensitivity represents a significant leap forward, allowing for the identification of hydrogen at concentrations previously undetectable under standard atmospheric pressure.