Hyper-Resolution Isotopic Analysis of Perfluorocarbons in Ambient Air Using a Multi-Pass Cavity Ring-Down Spectrometer and Bayesian Calibration

**Abstract:** This paper details a novel approach for high-resolution isotopic analysis of perfluorocarbons (PFCs) – potent greenhouse gases – in ambient air using a modified Picarro Cavity Ring-Down Spectrometer (CRDS). The technique leverages a multi-pass cell within the CRDS to enhance absorption pathlength combined with a Bayesian calibration framework to account for instrument response uncertainties and spectral overlap effects. This configuration facilitates isotopic analysis at unprecedented resolution (δ¹³C and ¹⁹F) with improved precision, enabling refined source apportionment and climate policy assessment. The system is readily commercializable within a 3-5 year timeframe by targeting environmental monitoring agencies and industrial emissions compliance programs.