Unrivaled accuracy in measuring rotational transitions of greenhouse gases: THz CRDS of CF.

Tetrafluoromethane CF is the most abundant perfluorocarbon in the atmosphere, where it is designated as PFC-14. This greenhouse gas is very stable, has an atmospheric lifetime of 50 000 years, and a high greenhouse warming potential 6500 times that of CO. Over the last 15 years, its atmospheric concentration has increased at a rate of 0.

The ro-vibrational ν mode spectrum of methane investigated by ultrabroadband coherent Raman spectroscopy.

We present the first experimental application of coherent Raman spectroscopy (CRS) on the ro-vibrational ν mode spectrum of methane (CH). Ultrabroadband femtosecond/picosecond (fs/ps) CRS is performed in the molecular fingerprint region from 1100 to 2000 cm, employing fs laser-induced filamentation as the supercontinuum generation mechanism to provide the ultrabroadband excitation pulses. We introduce a time-domain model of the CH ν CRS spectrum, including all five ro-vibrational branches allowed by the selection rules Δv = 1, ΔJ = 0, ±1, ±2; the model includes collisional linewidths, computed according to a modified exponential gap scaling law and validated experimentally.

Nitrogen-Broadening Parameters for Atmospheric Spectra Modelling of the ν Band of SF.

The infrared absorption of the ν band region of SF at temperatures spanning the 130 to 297 K range, has been reexamined using improved instrumentation with one goal: to estimate the broadening of parameters by nitrogen gas. These parameters are compared to previous literature predictions and an extended set of IR cross-sections is proposed and compared to other existing datasets.

High enthalpy source dedicated to quantitative infrared emission spectroscopy of gas flows at elevated temperatures.

The High Enthalpy Source (HES) is a novel high temperature source developed to measure infrared line-by-line integrated absorption cross sections of flowing gases up to 2000 K. The HES relies on a porous graphite furnace designed to uniformly heat a constant flow of gas. The flow compensates thermal dissociation by renewing continuously the gas sample and eliminating dissociation products.