Vacuum-ultraviolet absorption cross-sections of functionalized cyclic hydrocarbons: Six-membered rings

Simulation of the VUV Absorption Spectra of Oxygenates and Hydrocarbons: A Joint Theoretical–Experimental Study

“…The experimental method used to measure absorption cross sections is described in detail by Doner and co-workers . As a concise overview, differential absorption spectroscopy measurements were conducted on species in the gas phase using a temperature- and pressure-controlled flow cell with a path length of 10 cm.…”

“…That signal showed no signs of spectral interference from contamination (e.g., oxygen or water), where 3 < n < 5. x̅ ( E ) = ∑ x ( E ) n Given the number of measurements used to produce the absorption cross sections, signal deviation was accounted for to quantify repeatability error using calculations of the standard deviation, s ( E ), standard error, ϵ( E ), and the ratio of standard error-to-average, r ϵ , x̅ , for a given spectrum: s ( E ) = ∑ ( x false( E false) − x̅ false( E false) ) 2 n − 1 ε ( E ) = s ( E ) n r ε , x̅ ( E ) = ε x̅ Two main sources of experimental uncertainty were quantified: (1) gas-phase concentration within the absorption region and (2) experimental repeatability. Details and methods for calculating both types of uncertainty are outlined in Doner et al All uncertainties were determined assuming errors as random variables with uniform distribution, which enables application of the root-sum-square (RSS) method to calculate an overall uncertainty for cross sections as a function of photon energy.…”

“…For spectral regions above a threshold of 2% of maximum absorbance, a standard-error-to-average ratio of <5% is typical . The standard-error-to-average ratio, r ε , x̅ ( E ) , is used as a measure of repeatability, and determined for all species.…”

“…Vacuum ultraviolet (VUV) absorption spectroscopy is a powerful analytical tool that can probe high-energy valence electronic transitions (e.g., σ → σ* and n → σ*) and Rydberg transitions, which are common in hydrocarbons and oxygenates. − By accessing these transitions, a molecule’s VUV absorption spectrum allows the definitive detection of the target species, a more complete description of the species’ electronic structure, and quantitative, isomer-resolved speciation measurements. − Despite its applicability, experimental VUV spectroscopy does have limitations. Primarily, it requires the target molecule to be feasible to synthesize and isolate at sufficient yield and purity.…”

Chemical kinetics of cyclic ethers in combustion

“…A third promising technique is molecular absorption spectroscopy, which allows probing a large variety of species during combustion experiments [23]. Although to the best of knowledge of the authors, this technique has not yet been used to detect CE in oxidation processes, Rotavera and coworkers [289] recently published measurements of absorption crosssections in the vacuum ultraviolet (5.17 -9.92 eV) using differential absorption spectroscopy for five-and six-membered cyclic species including CEs.…”