Accueil Dispositifs et équipements Pôle IC - Isotopie Chimie Pyr-IRMS & Water Isotope Laser Analysis

Pyr-IRMS & Water Isotope Laser Analysis

These instruments are dedicated to isotopic analysis (δ¹⁸O, δ¹⁷O, ¹⁷O excess, δD) of organic matter and water at natural or enriched abundance, as well as %O content.

A Pyrolyzer (Pyr) and a High-Temperature Elemental Analyzer (EAHT) coupled to an Isotope Ratio Mass Spectrometer (IRMS). Oxygen and hydrogen from finely ground, micro-weighed solid samples in silver capsules or liquid samples extracted by cryoextraction from leaves, wood, or soil are converted into simple, pure gases through high-temperature combustion/reduction or pyrolysis. The gases are then dried, purified, and separated. After concentrations are measured using a Thermal Conductivity Detector (TCD), the gases are transferred to the IRMS via a carrier gas (He). Each gas molecule is ionized under high voltage, and the resulting ions are separated in a magnetic field according to their masses. Different isotopologues are collected in Faraday cups, and the results are normalized and standardized.

An Optical Cavity Ring-Down Laser Spectrometer (LAS) allows injection of liquid samples (H₂O) or cryo-extracted samples into a near-perfect reflectance chamber, where two near-infrared lasers at specific wavelengths target the isotopologues (H₂¹⁸O, H₂¹⁶O, HD¹⁶O or H₂¹⁸O, H₂¹⁷O) along a 20 km optical path to intercept all target molecules. Results are normalized and standardized.

Five configurations are available: Pyr only (%O), Pyr-IRMS (δ¹⁸O), LAS-EAHT-IRMS (δ¹⁸O), LAS-EAHT-IRMS (δ²H), or IRIS (δ¹⁸O, δ²H).

Applications:

  • Modelling of biogeochemical cycles (soil-tree-atmosphere continuum)
  • Water-use efficiency and soil water availability
  • Functioning of trophic networks
  • Competition between forest species

 

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Rédaction : CM Date de création : 17 janvier 2022 Date de modification : 26 août 2025