VUV Photoionization Cross Sections of HO2, H2O2, and H2CO

Dodson, Leah G.; Shen, Linhan; Savee, John David; Eddingsaas, Nathan C.; Welz, Oliver; Taatjes, Craig A.; Osborn, David L.; Sander, Stanley P.; Okumura, Mitchio

doi:10.1021/jp508942a

Cited by 67 publications

(66 citation statements)

References 100 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…53−57 The mole fraction profiles were derived with eq 1 by using published photoionization cross sections. 45,47,51 These new data shown here can serve as validation targets for present and future mechanisms, and consequently, we compared our experimental data with modeling results using the three mechanisms mentioned above.…”

Section: Resultsmentioning

confidence: 98%

“…In our validation study and applications, we attempted to minimize interference from these latter two effects by restricting attention to photon energies within ∼1 eV of the photoionization threshold. Examples of complications caused by poor Franck−Condon overlaps, fragmentation, and lowlying electronically excited states of the cation are discussed below for HPMF, CH 3 45 Detailed comparisons of eqs 2 and 3 with the experimental results for these 15 species are given in Supporting Information (Figures S2−S16), where the comparisons were used to assign a 2σ error bar of a factor of 2 to the theoretical cross sections.…”

Section: Experimental Details and Data Evaluationmentioning

confidence: 99%

See 1 more Smart Citation

Quantification of the Keto-Hydroperoxide (HOOCH₂OCHO) and Other Elusive Intermediates during Low-Temperature Oxidation of Dimethyl Ether

et al. 2016

Self Cite

View full text Add to dashboard Cite

This work provides new temperature-dependent mole fractions of elusive intermediates relevant to the lowtemperature oxidation of dimethyl ether (DME). It extends the previous study of Moshammer et al. [J. Phys. Chem. A 2015, 119, 7361−7374] in which a combination of a jet-stirred reactor and molecular beam mass spectrometry with singlephoton ionization via tunable synchrotron-generated vacuumultraviolet radiation was used to identify (but not quantify) several highly oxygenated species. Here, temperature-dependent concentration profiles of 17 components were determined in the range of 450−1000 K and compared to up-to-date kinetic modeling results. Special emphasis is paid toward the validation and application of a theoretical method for predicting photoionization cross sections that are hard to obtain experimentally but essential to turn mass spectral data into mole fraction profiles. The presented approach enabled the quantification of the hydroperoxymethyl formate (HOOCH 2 OCH 2 O), which is a key intermediate in the low-temperature oxidation of DME. The quantification of this ketohydroperoxide together with the temperature-dependent concentration profiles of other intermediates including H 2 O 2 , HCOOH, CH 3 OCHO, and CH 3 OOH reveals new opportunities for the development of a next-generation DME combustion chemistry mechanism.

show abstract

Section: Resultsmentioning

confidence: 98%

Section: Experimental Details and Data Evaluationmentioning

confidence: 99%

Quantification of the Keto-Hydroperoxide (HOOCH₂OCHO) and Other Elusive Intermediates during Low-Temperature Oxidation of Dimethyl Ether

et al. 2016

Self Cite

View full text Add to dashboard Cite

show abstract

“…(a) Scaled to agree with the absolutely-calibrated photoionisation cross section of Dodson et al (2015) where they overlap. …”

Section: O + 2 -Oxygen Ionmentioning

confidence: 99%

“…A photoionisation cross section was assembled by combining absolute and relative measurements of H 2 O + 2 production (Dodson et al 2015;Litorja & Ruscic 1998) and assuming a low production of fragmented ions.…”

Section: H 2 O 2 -Hydrogen Peroxidementioning

confidence: 99%

“…The photoionisation cross section is measured near threshold by Dodson et al (2015) and at shorter wavelengths the photoabsorption cross section was scaled by the ionisation efficiency of Cooper et al (1996). This ionisation efficiency approaches 100% at longer wavelengths than that measured by Mentall et al (1971), which suffers from an estimated 30% uncertainty.…”

Section: H 2 Co -Formaldehydementioning

confidence: 99%

See 1 more Smart Citation

Photodissociation and photoionisation of atoms and molecules of astrophysical interest

Heays

Bosman

Dishoeck

2017

A&A

405

442

View full text Add to dashboard Cite

A new collection of photodissociation and photoionisation cross sections for 102 atoms and molecules of astrochemical interest has been assembled, along with a brief review of the basic physical processes involved. These have been used to calculate dissociation and ionisation rates, with uncertainties, in a standard ultraviolet interstellar radiation field (ISRF) and for other wavelength-dependent radiation fields, including cool stellar and solar radiation, Lyman-α dominated radiation, and a cosmic-ray induced ultraviolet flux. The new ISRF rates generally agree within 30% with our previous compilations, with a few notable exceptions. Comparison with other databases such as PHIDRATES is made. The reduction of rates in shielded regions was calculated as a function of dust, molecular and atomic hydrogen, atomic C, and self-shielding column densities. The relative importance of these shielding types depends on the atom or molecule in question and the assumed dust optical properties. All of the new data are publicly available from the Leiden photodissociation and ionisation database. Sensitivity of the calculated rates to variation of temperature and isotope, and uncertainties in measured or calculated cross sections, are tested and discussed. Tests were conducted on the new rates with an interstellar-cloud chemical model, and find general agreement (within a factor of two) in abundances obtained with the previous iteration of the Leiden database assuming an ISRF, and order-of-magnitude variations assuming various kinds of stellar radiation. The newly parameterised dust-shielding factors makes a factor-of-two difference to many atomic and molecular abundances relative to parameters currently in the UDfA and KIDA astrochemical reaction databases. The newly-calculated cosmic-ray induced photodissociation and ionisation rates differ from current standard values up to a factor of 5. Under high temperature and cosmic-ray-flux conditions the new rates alter the equilibrium abundances of abundant dark cloud abundances by up to a factor of two. The partial cross sections for H 2 O and NH 3 photodissociation forming OH, O, NH 2 and NH are also evaluated and lead to radiation-field-dependent branching ratios.

show abstract

Absolute Photoionization Cross Section and Dissociative Ionization Pathways of Alpha‐Pinene

Rodriguez,

Taatjes,

Meloni

2024

ChemPhysChem

Self Cite

View full text Add to dashboard Cite

The absolute photoionization cross section of the monoterpenoid, alpha‐pinene (AP), is presented together with the relative photoionization cross sections of its dissociative fragments for the first time. Experiments are performed via multiplexed vacuum ultraviolet (VUV) synchrotron photoionization (PI) mass spectrometry in the 8.0–11.0 eV energy range. Experimental work is conducted at the Advanced Light Source of the Lawrence Berkeley National Laboratory. Dissociative fragments were identified at m/z 121, 94, 93, 92, and 80. The photoionization cross section for the parent mass at 11.0 eV was determined to be 17±4 Mb with a total ionization cross section of 92±23 Mb at the same photon energy. Experimental appearance energies of dissociative ionization fragments and potential dissociative ionization pathways calculated at the G4 level of theory are presented as well.

show abstract

VUV Photoionization Cross Sections of HO₂, H₂O₂, and H₂CO

Cited by 67 publications

References 100 publications

Quantification of the Keto-Hydroperoxide (HOOCH₂OCHO) and Other Elusive Intermediates during Low-Temperature Oxidation of Dimethyl Ether

Quantification of the Keto-Hydroperoxide (HOOCH₂OCHO) and Other Elusive Intermediates during Low-Temperature Oxidation of Dimethyl Ether

Photodissociation and photoionisation of atoms and molecules of astrophysical interest

Absolute Photoionization Cross Section and Dissociative Ionization Pathways of Alpha‐Pinene

Contact Info

Product

Resources

About

VUV Photoionization Cross Sections of HO2, H2O2, and H2CO

Cited by 67 publications

References 100 publications

Quantification of the Keto-Hydroperoxide (HOOCH2OCHO) and Other Elusive Intermediates during Low-Temperature Oxidation of Dimethyl Ether

Quantification of the Keto-Hydroperoxide (HOOCH2OCHO) and Other Elusive Intermediates during Low-Temperature Oxidation of Dimethyl Ether

Photodissociation and photoionisation of atoms and molecules of astrophysical interest

Absolute Photoionization Cross Section and Dissociative Ionization Pathways of Alpha‐Pinene

Contact Info

Product

Resources

About

VUV Photoionization Cross Sections of HO₂, H₂O₂, and H₂CO

Quantification of the Keto-Hydroperoxide (HOOCH₂OCHO) and Other Elusive Intermediates during Low-Temperature Oxidation of Dimethyl Ether

Quantification of the Keto-Hydroperoxide (HOOCH₂OCHO) and Other Elusive Intermediates during Low-Temperature Oxidation of Dimethyl Ether