iRIS-III Frequently Asked Questions

PEM Integrated Radiocarbon Infrared Spectrometer (iRIS-III™) 14CO2 Analyzer

  1. What does the iRIS carbon dioxide isotope analyzer do?

The iRIS 14CO2 carbon dioxide isotope analyzer measures the quantity of 14C, or radiocarbon, in carbon dioxide (C02) for discrete gaseous samples analyzed as pure CO2 below fraction modern 14C of 1 (F14C ≤ 1). The iRIS is a portable instrument that can be assembled on a laboratory bench top, deliver results in under an hour and at a fraction of the cost of traditional analysis. The results can be reported as Fraction Modern radiocarbon[1] or as radiocarbon activity concentrations[2]. The iRIS employs a solid state laser to selectively excite 14CO2 molecules. The iRIS analyzers are linked securely to the internet to ensure that the same reference and baseline data are integrated across analyzers for comparable results. Radiocarbon is analyzed as a tracer for fossil fuel derived CO2 emissions to the atmosphere. Radiocarbon is also employed in dating of archaeological materials and is used extensively in the oil and gas and nuclear industries among others. The portable iRIS technology represents a breakthrough in radiocarbon analysis. Typically, radiocarbon is analyzed at regional facilities by Accelerator Mass Spectrometry[3] (AMS) at high cost per sample and days to weeks analysis turnaround time. Our goal is to make the iRIS and high precision radiocarbon measurements as ubiquitous as CO2 concentration measurements that now reach across the planet and number in the millions of measurements annually.

  1. What are the key features of the PEM iRIS?  

First of all, to our knowledge, portable and high precision radiocarbon analyzers are not yet commercially available.  The challenge of developing a high precision portable 14CO2 analyzer are formidable. Previous efforts while marking progress have not yet resulted in a commercial device with precision similar to AMS. However, the iRIS promises to break through technological  barriers to successful commercialization. The core instrument comprising the iRIS is under development by the National Institute of Technology under a technology license agreement between PEM and NIST.  The key features of the iRIS are:

  • High precision 14CO2 CRD linear absorption platformThe quantitative measurement of 14C in gas-phase samples of CO2 with F14C < 1  has been demonstrated with cavity ring-down spectroscopy in the linear absorption regime.  The combination of a high-fidelity stabilized frequency axis, an ultra-sensitive CRDS detection scheme, and the use of an ab initio transition intensity provides the quantitative optical detection of 14C at F14C < 1 on an absolute scale (Fleisher et al. 2017)[4] [5]. This approach simplifies the analysis and the hardware configuration in a calibration-free instrument configuration. The iRIS approach differs from the saturated absorption cavity ring-down (SCAR) configuration[6] reported recently for F14C < 1 and for analyzers developed for enriched 14CO2 (F14C > 1) applications. The expected precision for the iRIS is in line with typical AMS results based on development efforts now underway.
  • Expected precision for 14CO2The iRIS generation I analyzer uncertainty is ~ 11.2% F14C (1 sigma) as reported (Fleisheret al. 2017). The iRIS generation III (iRIS-III) analyzer, now under development is expected to attain an uncertainty of  < 1% Fraction Modern with additional uncertainty reduction for successive models. The rapid evolution of precision to match AMS precision is our highest priority.
  • iRIS pure CO2 sample compositionThe iRIS employs pre-concentrated and pure CO2 for analysis with negligible N2O concentration to eliminate potential interferences.  The CO2 can be admitted via sealed glass ampoules or vessels with stopcock valves or via our PEM Interface to a variety of peripheral analyzers.
  • Integration of external sample modules and in-line analyzers: PEM will offer the iRIS with integrated external modules for automated sample handling including an elemental analyzer and gas delivery interface. In-line external analyzers could include 12CO2 and 13CO2 and corresponding isotopologues (12CO2 , 13CO2 , CO17O and CO18O) from gases resulting from trapping, combustion or extraction from the aqueous phase. Radiomethane (14CH4) analysis requires an external module for isolation and combustion of CH4 followed by release of resulting CO2 into the iRIS inlet. iRIS configurations are described in the iRIS reservation system.
  • Integrated 14C Reference System (sir-14C)–The First SI-traceable Radiocarbon Reference. Currently, radiocarbon analyses are referenced against a gas standard typically produced from a distributed solid reference material such as NBS Oxalic Acid (SRM 4990B, OX-1).[7] However, the sir-14C provides a reference system that is based on the International System of Units (e.g., SI units system[8]), an approach pioneered by the National Institute of Standards and Technology (NIST). The PEM sir-14C eliminates the need for reference gas production for each analyzer and provides real-time internet based  intercomparison of all analyzers. However, the strict requirement to link the iRIS analysis with known 14C reference material is maintained by our sir-14C Master Reference Facility. Every iRIS analysis is verified and certified by online connection to our Master Reference Facility providing a time stamp and verification data linked to our system. The sir-14C means that no matter how many iRIS analyzers are in operation they will each have verified and compared reference certification. The iRIS makes use of remarkable relative precision of ab initio CO2 line intensities when compared to accurate experiments as reported in recent HITRAN reference data in combination with ultra-precise measurements of temperature and pressure. The iRIS operation with “gas-free” reference specifications is capable of measuring radiocarbon on an absolute scale, and thus potentially capable of replacing the current artifact-based scale with one that is entirely SI-traceable (Fleisher et al. 2017). All of the online sir-14C data are protected with banking-level encryption to ensure privacy and data integrity to end-users.

  3.  When and how will the iRIS analyzer be available for purchase? The initial iRIS-III analyzer production is expected to begin in 2019. Initial iRIS analyzers can be reserved for delivery in 2019 by completing an online form here. The reservation system allows configuration of the iRIS with multiple peripherals, purchase and finance options and other information.

  4. Is the iRIS durable enough to be used for field (non-laboratory) applications? The initial iRIS analyzers will require a typical laboratory setting, powered instrument shed or mobile laboratory for operation. Ruggedization of the iRIS to support remote field deployment is under development. Power requirements and space considerations are provided in the preliminary specification sheet.

[1] “Radiocarbon Data & Calculations : NOSAMS.”


[3] “Accelerator mass spectrometry – an overview | ScienceDirect Topics.”

[4] “Optical Measurement of Radiocarbon below Unity Fraction Modern by ….”

[5] “Spotlights – American Chemical Society.” 21 Sep. 2017,

[6] “Saturated-Absorption Cavity Ring-Down Spectroscopy.” Accessed 25 Feb. 2018.


[8] “The International System of Units (SI) – NIST.” Accessed 25 Feb. 2018.