Fractionation of Methane Isotopologues during Preparation for Analysis from Ambient Air.

Preconcentration of methane (CH) from air is a critical sampling step in the measurement of singly and doubly substituted isotopologue ratios. We demonstrate the potential for isotope fractionation during preconcentration onto and elution from the common trapping material HayeSep-D and investigate its significance in laser spectroscopy measurements. By altering the trapping temperature for adsorption, the flow direction of CH through the trap and the time at which CH is eluted during a desorption temperature ramp, we explain the mechanisms behind fractionation affecting δC(CH) and δH(CH).

Step Change in Improving the Accuracy of Nitrous Oxide Reference Materials for Underpinning Atmospheric Composition Measurements.

We have employed a new approach to quantify the amount fraction of nitrous oxide in a synthetic air matrix gas used to prepare high-accuracy reference materials of the same component. Until now, this was the largest contributor to the measurement uncertainty of nitrous oxide in air reference materials at atmospheric amount fractions (∼330 nmol mol), as identified in a recent international comparison. A novel preconcentration method has resulted in a measurement of 363 pmol mol of nitrous oxide in a synthetic air matrix gas with an expanded uncertainty of 27 pmol mol.

Boreas: A Sample Preparation-Coupled Laser Spectrometer System for Simultaneous High-Precision In Situ Analysis of δC and δH from Ambient Air Methane.

We present a new instrument, "Boreas", a cryogen-free methane (CH) preconcentration system coupled to a dual-laser spectrometer for making simultaneous measurements of δC(CH) and δH(CH) in ambient air. Excluding isotope ratio scale uncertainty, we estimate a typical standard measurement uncertainty for an ambient air sample of 0.07‰ for δC(CH) and 0.

HPCO-A Phosphorus-Containing Analogue of Isocyanic Acid.

We describe the isolation and spectroscopic characterization of the heavier phosphorus-containing analogue of isocyanic acid (HPCO), and its isotopologue (DPCO). This fundamental small molecule, which has been postulated to exist in interstellar space, has thus far only been observed at low gas phase concentrations or in inert gas matrices. In this report we describe its synthesis, spectroscopic properties, and reactivity in solution.